Merchant one payment api help

Im in the process of setting up my card processor and I was wondering if anyone would be willing to help me. They have a crazy api and i cant figure out for the life of me the proper way to submit form data to it. I dont need it to get shipping data or anything, i just need to process the payments and my company lets me get away with a minimal amount of inputs. My gateway is merchant one if anyone has any prior experience with them. also one of the BIG problems im having is right now my test script has the username and password as hidden form fields and i cant have that when i move beyond the demo account that im using to get it running, sorry ive been out of the PHP game for a couple years and im just starting to program again. I attached the api in a txt file and heres a link to a copy of the documentation. thanks.