Credit questions


Okay so I am 19 and don’t really have anyone to turn to when it comes to things like this so I’m hoping you guys could help me out. I want to start building my credit but I am also not trying to mess it up by not knowing what I am doing. Say for instance if I am given a $300 limit (I read online not to go over 10%) does that mean not to spend more than $30 on my credit card for just that month? Or can I use it all I want just pay it off on the day it’s supposed to be paid? Please don’t come for me I don’t have family or anything just trying to make it out here. Thanks in advance for any help

edit: thanks for the comments. I was kinda scared to ask for the help here bc some girls on here are so mean lol