From Halopedia, the Halo wiki
I appreciate the enthusiasm with editing the Multiplayer Elite page but keep in mind it is meant to only cover the player characters. Info regarding how Elite NPCs appear and act in Firefight is not relevant to the page at all.
The upload form can be found on the left side of the screen, but I'd highly recommend waiting until you have computer access before doing heavy editing - especially image uploading. We are fairly exacting when it comes to article and image standards. I'd really stress that it's worth reading the Manual of Style and doing small edits before starting to do large things.
Not sure what happened to the link there, but this one should work.
It depends on the page you're making; I'd recommend prototyping it on a personal sandbox before pushing it to the main space. We have a fairly active Discord that's a good place to seek feedback.