Need help with trailer light wiring

[Jakes-66-K10]

I am taking off a hitch from another truck, since this 3/4 ton will do alot better pulling now with front discs. Anyway, the couple of trailers I have use that 4 pin connector and they don't have trailer brakes.

How is the best way to hook this up correctly? I was thinking that I'd just crawl under and splice them into the white, green, yellow lines that run to my tail lights. Someone suggested not doing that though, because you have to use diodes or something to prevent the trailer lights from burning out.

I'm confused... and our trucks are old enough they don't make plug and play kits like new vehicles.