Hi Dennis, there are a few different ways to do it. Hopefully this article will help you - https://www.wikihow.life/Clean-the-Oven
Spray on oven cleaner, read label directions. If the oven is electric avoid spraying the heating elements. I’ve tried a few of the make your own oven cleaners....meh results. I would also put in siliconized oven mats...any thing that would stick to the bottom of the stove doesn’t stick. Just pull it out dump the gunk off, wipe and replace.
Read your oven manual which should specify what can and cannot be used on oven surfaces. Note that not all oven manufacturers permit use of liners on botttom of oven, as it can void warranty.
some walmarts have them, some catalogs have them