How to create/edit a gamemode?

Ive tried to make my own Gamemode and when I do its always a complete failure…
I try to take the original Sandbox Gamemode and change simple and small things and afterward everything is fucked up including the menu and Scoreboard even if I didn’t change anything for them.
I do have basic to moderate knowledge of lua.

You need to know lua.

Thanks for the help…
I think I know lua enough to where I can edit a Gamemode but,
when I change anything it interferes with the Menu and Scoreboard even if the code doesn’t
Like Ive made changes to like the noclip hook function and the
hook for spawning an object, like so when the Server Admin
spawns something it doesn’t add it to the amount of <objects> spawned.
It doesn’t change anything that has to do with drawing the menu or scoreboard but
It does error afterward.
Please don’t post something as pointless again.

after that last post I gave up until about 2 weeks ago and I started trying to do it again… But this time it works…