Suck dick

I’m super nervous to suck my mans dick but he wants me to and he goes down on me so I want to this saturday. I need advice on how to do it. Also I’m nervous because whenever I wipe his cum off my stomach and it touches my hand I gag so idk how im supposed to swallow it. One more thing, my jaw locks up whenever I eat a breadstick so I’m nervous I wont even be able to open my mouth wide enough. Do i just fold my lips back over my teeth and suck it I’m hella confused😂