You Can Use ((Mybb,vBulletin,SMF))

For Mybb System
http://www.mybb.com/
You can Host It Via http://www.000webhost.com/

For vBulletin
http://www.vbulletin.com/
It Will Be Hosted Automaticaly because when you apply for creating it makes for you domain and builder

For SMF
http://www.freeforums.org/
The Domain Going To Be domainname.freeforums.org to change it to domainname.tk use
http://www.dot.tk/ar/index.html