time cam belt adjudments

I have watched youtube bout it n only find one shitty video where the dude keeps putting the camera down cant hear him or see what he is doing. I don't even know if it's what is wrong with my 2001 honda cbr929rr it keeps backfiring n its sounds like it just fighting to start but won't got new spark plugs and made sure all plugs getting spark. i dont even kno how to fix the timing so if anyone can explain steps or recomend me a video id appreciate it alot