Learning How To Execute Assignment of Contractas

Hi everybody! I'm planning on doing Assignment of Contract as a start. Now these are the questions that I have: What is this the best contract for the seller (realtor-which I'll be doing business with) to fill out? The Assignment of Contract form is for the buyer which is found in the Forms and Docs? How do you calculate the Finders Fee and calculate the the grand total to present to the buyer and seller? Also, where can you locate the calculations for the Finders Fee and the grand total of the property? It's not listed under the Forms and Docs. Thank you.