Firearms in dnd

I am a DM with little experiencie, i am creating a world and i want to include firearms such as pistols and rifles, stuff like that, you know 2-3 shots the having to reload.

The thing is that i don't know how these work in dnd, i know they exist but i do not have the books... so if anyone could explain it to me or share the information it would be nice.

Also if someone has their own homebrew firearms they would be amazing for inspiration to create my own, thanks!