I am trying to install on software on linux server but its saying please install mcrypt / mhash
What is mcrypt/mhash and how can I install it. Please let me know.

mcrypt is used to encrypt data, which requires the mhash library to operate.

mcrypt: http://mcrypt.hellug.gr/mcrypt
mhash: http://mhash.sourceforge.net

You may also want to FTP to your Linux or Unix distribution's server and download from there.