How to install php extension

[vuong-bse]

I have some questions as below:

1. How to install php extension
2. After install I got php command not found. I think not have php-cli. I cannot use yum install php- (because got php5)
3. How is php sock used?
   Thank you

[vuong-bse]

I find solutions: ln -s /home/lemp/php/bin/* /usr/bin