how to use swap

hello im already set swap but for now its still 0
and this is my information of memory my vps

top - 08:32:13 up 4 days,  3:23,  0 users,  load average: 0.08, 0.15, 0.56
Tasks: 106 total,   1 running, 105 sleeping,   0 stopped,   0 zombie
Cpu(s):  3.0%us,  0.8%sy,  0.8%ni, 95.1%id,  0.2%wa,  0.0%hi,  0.0%si,  0.1%st
Mem:   1020128k total,   536484k used,   483644k free,    16432k buffers
Swap:        0k total,        0k used,        0k free,   170556k cached

also im just put one wordpress in here but why its consume untul 5364 memory thanks before. and sometimes its until make my db hang and restarting.

ideally you don't want a LAMP server using swap. If you're swapping you need more memory.