not sure if this is right place:dont-know:

im making an iorn hands army and was wondering i have a venrable dreadnaught for my hq choice can he join a unit of space marines??:dance:

First of all, I am not sure if you can have a venerable dreadnought as your HQ choice, I think only Space Wolves can do this (I could be wrong though).
Onto the question. No, he cannot. The dreadnought is not an independant character, and thus cannot join squads. Sorry.

Sorry, I only play WHFB, but I can tell you that if you scroll down to the 40k section, you should find a rules help forum.



edit:
40k Rules Help - Librarium Online (http://www.librarium-online.com/forums/40k-rules-help/)