Which paintball gun should i use?

Im goin to boss paintball tomoro, n this is the first time i have evr played paintball. Im not all that scared, im just not sure which gun to use. THe rentals there are the smart part vibes and sp1s paintball guns and i have the spyder rt-l. I dont know which one i should use. I have nvr played and dont know much about these guns soo i do need help deciding which one to use. Plz answer asap! thank you with all the help