How to make a script that when a part touched another part that I want ?

This is more of a request for a script than a request for scripting HELP, but since I'm here, I'm going to help you get what you need.

If you are still struggling, please supply us with where the part is located, what the touching part is a descendant of or anything important of that matter.

-- I'm just going to assume that your parts are in the workspace, so I've set it up for you this way.
local Part1 = workspace["Part name here."]
local Part2 = workspace["Part name here."] -- Make sure the names of the parts don't match.

Part1.Touched:Connect(function(Hit)
	if Hit == Part2 then
		print("Part2 touched Part1")
	end
end)