Iowa has a large state association and will certainly have a rondy some time this summer. If you get a copy of Trapper and Predator Caller you should be able to find contact information for the officers of the Association. Or of you are and NTA member there information is published in the American Trapper. If you have neither access to these post here and I'll PM you some contacts.
I say all this because one of the best ways to get started is to get with some good trappers in your area; face to face is even better.