I created a theme and I want to use it + general theming help?

[xnrdotone]

Hello there, I made an ugly theme called "386" that no one would use for my site, it looks like this:

I want to use this theme on my ugly website and I'm assuming you won't be willing to add this to the official theme repo. How can I use it locally?

There are also a few problems with the theme, as you can see the "Sign up" button has a darker border and I don't know how to remove it I also want to change the font to something more classic and remove the avatars, are these possible?