Need help writing a grant for an LCD projector for my art class K-8. Any help would be greatly appreciated

I've never done one, but...
Who are you asking for the grant, a charitable trust? Manufacturer?
I would write to manufacturers.
I would simply tell them what your school budget is for art, how many students, and some numbers re average income, cost of living, and unemployment for your state or locale.
Facts and figures, basically. Keep it simple. It's a small request.

Check out the website Professional Grant Writer, Grant Writing, Grant Proposal Writing & Grant Research. They have a bunch of grants listed and they will help you write a grant. Sometimes their services are are free, but sometimes they charge a small fee. (You will need to ask.) My point is to tell you to look there to see if there are any grants listed for your projector. American Honda has a listing for grants up to $75,000 in the areas of STEM. Are you in the U.S.