Will do this in the topic because that's what it's for.
Requirements
You need to have a SA:MP server, obviously, and a webhost (could be localhost for development purposes)
Your server needs to save the data somewhere, either in INI files or in a database, it doesn't really matter
If you match both requirements, you can make a control panel using HTML/CSS for the front-end, JS for the communication with the back-end and PHP for the back-end itself, or Python or whatever language suits you best that runs on the server.
The first and probably most important thing to implement is a login system, so non-admins can't take admin actions. Use the hashing system your server use to make it possible to make people login with their login credentials, and also think about security to prevent against CSRF, MITM, Bruteforce, XSS attacks and SQL injection. Most of these are pretty common nowadays (although MITM is an exception but can be easily prevented by having an SSL certificate) and it is not that hard to prevent it.
When you have your authentication and security done, you can move on to the actual control panel. Here you can think about (temp)bans, ip(range)bans, unbans, warnings, profiles and adjusting them, promoting/demoting admins/helpers and more like that.
After you got all your features, make sure to debug all your features and make sure your security is tight before you release it.
To upload it to your website, if you worked on localhost for development, use an FTP client like
FileZilla to upload the files to your webhost.
Here are a few resources which can be useful when making an ACP/UCP:
https://almsaeedstudio.com/
http://php.net/
http://www.w3schools.com/
