problem with a program for the second language

hi
I am using now for my web site a persian word press http://www.iranvij.org. Now I am going to install an english version for my web site and hopefully in the future a german version. My problem is : HOW can I install the second program for the second language? I have learned every thing about word press by myself. In Iran especially in my region it is really difficult to find an expert. Please help me. I have to install this program as soon as possible.
Thanks