I am new to speedrun but I am kind of confused to recording and stuff. Do I need to use a specific recording? or not and do i need to upload on yt? or other platform.

You don't need to use any specific program to record, anything that clearly captures the full gameplay is fine. That said, most people use OBS.

It's easiest if you can upload your vids on youtube, but any video-hosting platform that permanently stores VODs should be fine.

Thank you for answering the question, appreciate it!