The details can be found here at this post. Basically you have to find a model yours that you like or is your favorite and make a post about it. Then comment or email Mr Warflake and let him know. I been trying to figure out what I would do for the post since I heard about the contest and finally landed on two things.
My favorite model is usually the last one I have finished, and I am not going to lie I think this is because I am slowly getting better and better as a painter. So as I push myself and practice I like my newest model the best. Currently the last challenge for myself was my pink prince with wings that I have shown here before. He's not the best on the table since he is a kajillion points for wings, but I play him often anyway just because I liked the model. He's a pink prince with a blue guy coming out of him as a throw back nod to the fluff.
I do have a battle wagon that I really like. I have had a ton of people that comment that they would like to see how it comes out when painted and this contest is a excuse to post up some pictures online for a army I haven't touched in some time. So here is a converted battle wagon from a chimera. I have four battle wagons and since I am annoyed to have the same model for anything I decided that at some point the orks who always play IG would have scavenged the battle field and made something a bit more orky. =) This is normally the ride for my KFF mech and the meganobs when I bring them.
It's ready to paint I just never made it back to the thing yet.