Go into /admin/index.php. Unless you want all of your new staff members to be admins, you will need to add another usergroup for moderators. You can do this by clicking "Create New Group" in the left menu. After you've done this, you should set the group's permissions by going into "Edit Group Permissions". You can then add users to the group by going into /admin/edit_user.php.

The default usergroup for admins is 1, and for normal users it is 2. If you've added a moderator usergroup, it will be group id 3.

Silly me I was logged into the account that I was trying to make admin.

Ignore this:
When I go on any /admin/ files it just takes me back to index.php, the one with the image counter not the admin index.php.

That'd do it.

Any certain files that I should modify to make the site look good?

Because I would like to make a better theme then the default.

Most of the site's style comes from default.css in the root directory. There's also a copy in /extra if you mess up.

There are some parts that are hard-coded into the site's HTML. For these, you will need to directly modify the source code files for the particular page you wish to modify. Don't worry, you probably won't need to do anything to the PHP; just change some of the HTML that the PHP is wrapped around. You can find source code files for the individual pages in /includes. The HTML will be located either inside echo() or print() statements, or outside of the <?php ?> tags. If you're going to modify these files, I recommend making a copy of the files as they were before you edited them (or keep a copy of the source ZIP) in case you make a mistake.

Is there a way to change the text color in the forum because it does not fit my theme sadly.

Link: cloverpic.hol.es/index.php?page=forum&s=view&id=2

Edit: How does rule34.xxx have gelbooru 0.2 when it has not been released to the public.

Rule34.xxx has Gelbooru 0.2 because Slayerduck, the owner of Rule34.xxx, is a personal friend of lozer's, and paid for the software. Rule34.xxx is also indirectly and directly affiliated with Gelbooru since we share rack space and image servers at the datacenter.

To change the text color in the forums, try searching for the block of CSS titled "div#forum > div.post".

You will probably want to change most of the CSS blocks with div.post in their titles. I'm also seeing the same issue with comments in your comment listing and on post pages.

How do I ban IP's?

You will need to manually add an entry to the database to ban anonymous IPs. I recommend installing phpMyAdmin to make manually modifying the database easier if you haven't already. When you do this, you should leave the user field empty so that someone can't accidentally register a user account with a banned username.

Otherwise, banning a user account will also automatically ban all IP addresses associated with that user account.

Thanks, the host I use luckly already has phpmyadmin installed what is good.