Hey jbdetd.1, welcome to the forum. I don't know what kind of slide you have (electric or hydraulic), but most slides require that the RV be fairly level side-to-side and front-to-back before using. Make sure there is nothing in the way when you bring it in or that will fall over when you extend it. There should be a switch somewhere in the RV that will operate the slide.
On our RV we have to disconnect the 115 V cord plugged into the main body of the RV that provides electricity to the slide electrical outlets before extending or retracting it.
Welcome to the forum. If its a MH slide, my ignition key has to be in Acc post ion for the slides to work and as DL says there is a switch someplace for each slide. My switch is black and you have to hold it in the open or close post ion until the slide is fully extended or retracted. My slides are electric.
AS STATED BEFORE WELCOME I have a class A and my ignition switch as to be on emergency brake on and level. my switch for the slides are above the entrance door in the cabinet. Post back when yoy solve your problem and let us know your out come.