Help analyzing results from free -m and top

Hi,

I am new to managing VPS i managed to get my 512 Linode with LEMP up and running. I have run these commands free-m and top but not sure how to decipher the results.

I have one wordpress blog running on the linode these are the results

Mem: 497 419 78 0 19 186

-/+ buffers/cache: 213 284

Swap: 255 0 255

2083 www-data  20   0 56836  25m 4660 S    0  5.1   0:03.55 php5-fpm                            
 2085 www-data  20   0 57084  24m 4296 S    0  5.0   0:02.85 php5-fpm                            
 2078 www-data  20   0 57052  24m 4308 S    0  5.0   0:02.45 php5-fpm                            
 2084 www-data  20   0 56396  24m 4384 S    0  4.9   0:03.45 php5-fpm                            
 2082 www-data  20   0 55556  23m 4612 S    0  4.8   0:03.34 php5-fpm                            
 2081 www-data  20   0 54784  23m 4488 S    0  4.6   0:02.60 php5-fpm                            
 2087 www-data  20   0 53936  22m 4360 S    0  4.4   0:03.18 php5-fpm                            
 2080 www-data  20   0 53156  21m 4456 S    0  4.3   0:03.36 php5-fpm                            
 2079 www-data  20   0 52380  20m 4660 S    0  4.2   0:03.24 php5-fpm                            
 2076 www-data  20   0 49236  17m 4296 S    0  3.5   0:03.11 php5-fpm                            
 2331 mysql     20   0 38788 7820 5336 S    0  1.5   0:00.54 mysqld                              
 2074 root      20   0 38700 4028 1364 S    0  0.8   0:02.66 php5-fpm                            
 2265 root      20   0  8380 2664 2108 S    0  0.5   0:00.03 sshd                                
 2661 root      20   0  8380 2620 2064 S    0  0.5   0:00.02 sshd                                
 2025 root      20   0  5600 2124 1708 S    0  0.4   0:00.00 sshd                                
 2278 kevin     20   0  4644 1928 1520 S    0  0.4   0:00.43 bash                                
    1 root      20   0  2732 1592 1204 S    0  0.3   0:00.78 init                                
 2277 kevin     20   0  8512 1392  828 S    0  0.3   0:00.90 sshd                                
 2673 kevin     20   0  8380 1388  824 S    0  0.3   0:00.31 sshd                                
 2147 ntp       20   0  4460 1356 1024 S    0  0.3   0:00.51 ntpd                                
 1923 syslog    20   0 28452 1272  980 S    0  0.2   0:00.09 rsyslogd                            
 2810 www-data  20   0  4644 1236  600 S    0  0.2   0:00.00 nginx                               
 3886 kevin     20   0  2572 1056  816 R    0  0.2   0:00.03 top                                 
 2811 www-data  20   0  4644  988  368 S    0  0.2   0:00.05 nginx                               
 2812 www-data  20   0  4644  988  368 S    0  0.2   0:00.04 nginx                               
 2813 www-data  20   0  4644  988  368 S    0  0.2   0:00.05 nginx                               
 1022 root      20   0  2492  908  636 S    0  0.2   0:00.09 upstart-udev-br                     
 1954 root      20   0  2428  896  704 S    0  0.2   0:00.01 cron                                
 2674 kevin     20   0  2052  792  648 S    0  0.2   0:00.22 sftp-server                         
 2809 root      20   0  4464  664  224 S    0  0.1   0:00.00 nginx                               
 1025 root      16  -4  2352  612  328 S    0  0.1   0:00.07 udevd                               
 1638 root      18  -2  2348  568  288 S    0  0.1   0:00.00 udevd                               
 1641 root      18  -2  2348  568  288 S    0  0.1   0:00.00 udevd                               
 2264 root      20   0  1840  556  476 S    0  0.1   0:00.00 getty                               
 1955 daemon    20   0  2300  356  224 S    0  0.1   0:00.00 atd                                 
 2007 root      20   0  2288  252  124 S    0  0.0   0:00.00 dhclient3                           
    2 root      20   0     0    0    0 S    0  0.0   0:00.00 kthreadd                            
    3 root      20   0     0    0    0 S    0  0.0   0:00.01 ksoftirqd/0                         
    4 root      20   0     0    0    0 S    0  0.0   0:00.00 kworker/0:0                         
    5 root      20   0     0    0    0 S    0  0.0   0:00.06 kworker/u:0                         
    6 root      RT   0     0    0    0 S    0  0.0   0:00.00 migration/0                         
    7 root      RT   0     0    0    0 S    0  0.0   0:00.00 migration/1                         
    8 root      20   0     0    0    0 S    0  0.0   0:00.00 kworker/1:0                         
    9 root      20   0     0    0    0 S    0  0.0   0:00.01 ksoftirqd/1                         
   10 root      RT   0     0    0    0 S    0  0.0   0:00.00 migration/2                         
   11 root      20   0     0    0    0 S    0  0.0   0:00.00 kworker/2:0                         
   12 root      20   0     0    0    0 S    0  0.0   0:00.00 ksoftirqd/2                         
   13 root      RT   0     0    0    0 S    0  0.0   0:00.00 migration/3                         
   14 root      20   0     0    0    0 S    0  0.0   0:00.00 kworker/3:0                         
   15 root      20   0     0    0    0 S    0  0.0   0:00.00 ksoftirqd/3                         
   16 root       0 -20     0    0    0 S    0  0.0   0:00.00 khelper                             
   17 root      20   0     0    0    0 S    0  0.0   0:00.00 kworker/u:1                         
   21 root      20   0     0    0    0 S    0  0.0   0:00.00 xenwatch                            
   22 root      20   0     0    0    0 S    0  0.0   0:00.00 xenbus                              
  133 root      20   0     0    0    0 S    0  0.0   0:00.02 sync_supers                         
  135 root      20   0     0    0    0 S    0  0.0   0:00.00 bdi-default                         
  137 root       0 -20     0    0    0 S    0  0.0   0:00.00 kblockd                             
  147 root       0 -20     0    0    0 S    0  0.0   0:00.00 md

I'd appreciate it if someone could tell me if this could be optimized further.

Thanks.