I am having very HIGH CPU usage... can someone help me to solve the problem.

Thats what top says:

top - 12:36:13 up 5 days, 1:33, 1 user, load average: 1.02, 0.90, 0.91
Tasks: 121 total, 2 running, 115 sleeping, 4 stopped, 0 zombie
Cpu(s): 36.6% us, 5.2% sy, 0.0% ni, 56.9% id, 1.3% wa, 0.0% hi, 0.0% si
Mem: 2074860k total, 2018108k used, 56752k free, 245400k buffers
Swap: 4096564k total, 0k used, 4096564k free, 1296920k cached

PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
16668 mysql 15 0 125m 19m 4152 S 26 1.0 8:49.41 mysqld
17039 apache 16 0 30772 8504 3180 S 24 0.4 0:49.76 httpd
16993 apache 15 0 30688 8820 3580 S 19 0.4 0:21.15 httpd
17046 apache 15 0 30736 8736 3448 S 16 0.4 0:32.78 httpd
16994 apache 15 0 30740 8488 3196 S 16 0.4 0:43.44 httpd
17103 apache 16 0 36080 13m 3504 R 12 0.7 0:14.10 httpd
16995 apache 15 0 30824 8904 3524 S 12 0.4 0:41.03 httpd
18403 apache 16 0 30688 8388 3148 S 12 0.4 0:16.62 httpd
19071 apache 17 0 30172 7312 2596 S 11 0.4 0:00.34 httpd
18288 apache 15 0 30724 8244 2964 S 9 0.4 0:09.41 httpd
17101 apache 15 0 31544 9568 3468 S 4 0.5 0:33.65 httpd
16997 apache 15 0 30708 8436 3176 S 2 0.4 0:46.85 httpd
17027 apache 15 0 30676 8764 3532 S 2 0.4 0:42.28 httpd
..............

I have alot users connecting to my domain which is pointed to my maching and showing web page through apache....

This isn't high. The load average is just over 1. I wouldn't be concerned until it was over 5 per CPU, and that a long-term value, not a peak value.

You've got plenty of available memory, so should the load go up higher, I would suspect that MySQL hasn't been properly optimized. Look to that if you really need to improve performance on this machine.