I try out Speedrunning, im very faster then the 1st One, im using the Cbosst and so on, BUT im slower then a Guy who NEVER can get this Time REALY, whos the One i can talk to?

There is a search bar on the top of the website. You can find the leaderboards, names and socials/discord server there

If you're accusing someone of cheating, and you have evidence, you may want to talk to the game's moderators about their run. If you don't have evidence, there's a good chance that they (and the community) just know more about speedrunning that game than you do, so ask them questions.