It's not really hard. Leave the lights in for sanding and polishing leverage, but tape off so you don't hit the rubber seal around the headlights or the paint. Then pull the headlights out and spray them. If the rubber seal around the headlights are in good condition, remove them before you spray the headlights and back on when you're done. You will have a big grin on your face when done and a great feeling of satisfaction of the job you did.
You should be able to get everything at like O'Reilly Auto Parts. This is the Polishing Pad I use.
https://www.oreillyauto.com/detail/masterpro-refinishing-4361/tools---equipment-16488/body-repair-16510/polishers--buffers--pads---bonnets-17962/polishing-foam-pad/67960/4511072?q=polishing+pad
Also wet sand the headlights and do
not use a circular motion. Just go up and down the headlight from top to bottom in one direction.
Dupli-Color Headlight Restoration Kit.
https://www.oreillyauto.com/detail/dupli-color-3391/chemicals---fluids-16461/paint---body-repair-16614/headlight-lens-repair-19109/headlight-restoration-kit/hlr100/4268130?q=Dupli-Color+HLR100
Mother's Mag & Aluminum Polish.
https://www.oreillyauto.com/detail/mothers-4408/chemicals---fluids-16461/cleaners-16866/waxes---washes-16651/metal--chrome---wheel-cleaner---polish-17738/mag-aluminum-polish/05100/4526703
Get some wet sanding paper, start at 800, then 1500, then 2000 and finish sanding with 3000 grit. Pick up some microfiber towels also.