So I just got 37:21 and I wanted to submit it to be in the leaderboard with, what for me is, a good time, but I see now that I need to give the demo and I dont know how. I mean I have a lot of .dem in my folder called run_X, I watched run_1 and looks like its only the first chapter but then it returns me to the menu, what do I really need to upload to get listed?

EDIT: Ok so I discovered that from run_1 to run_37 its my whole run, do I upload them and link all of them when I submit the run? I guess thats how it works but people shouldn't be able to cheat? I mean maybe not linking some demos that are useless (like failed jump boosts) to make it be a lower time.

Hello,

There's an area in the "Guides" section that explains it all. Here's the link: https://www.speedrun.com/hl1/guide/m3lo4

TLDR - you need to zip them into a file and submit with your run.