"my only problem is once i make changes to things in the material room can they be reversed?"

Edit > Undo. :)

"So how do I start of with just adding one light?"

Go to your light controls in the lower left. Select a light. Then click the little garbage can icon. Confirm that you want to delete. Do that until you have either none left, or only one. Then play with the settings of that individual light.

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Hardware: AMD Ryzen 9 3900X/MSI MAG570 Tomahawk X570/Zotac Geforce GTX 1650 Super 4GB/32GB OLOy RAM

Software: Windows 10 Professional/Poser Pro 11/Photoshop/Postworkshop 3