Is there a way that I can add a category? I made my own speedrun category and got a time of around 9 minutes and 56.85 seconds.

if you go to the all games section there is a button to request a new game.

Here is the link https://www.speedrun.com/knowledgebase/supporthub/request-game-or-series

Or, if it’s a new category you want added to an existing game, ask in that game’s forum or discord.

If you let us know what game it is we can provide more specific advice.