I want to study about computers , microsoft word , power point , excel etc on internet if anyone has some sites names . I tried in GCF global learning but everytime it shows the slots for online courses are full 
Pls if someone can help me so as I could sign in a good site and earn a certificate online?
Hello Nima:
the one that I know because I studied and worked there is DELL Learn University. Dell offers a bunch of online courses. Here is the link so you can check them:
http://www.learndell.com/Dell/