ssh-keygen -t ed25519
This will generate two files, a private key and public key, which you will use to authenticate with the server. As a rule of thumb, the private key file should never need to be copied to your clipboard - it's a private secret. The public key will be sent to the server - it ends in .pub.
By default (if you press enter through all the prompts), it will create two files in the ~/.ssh/ directory - one called id_ed25519 (the private key) and another called id_ed25519.pub (the public key). The commands below assume this. If you've already set up an ssh-key in the past, you can just use that one.
cat ~/.ssh/id_ed25519.pub
Now, we are going to send that key to our server. Copy the output (the key) and in the CTF League discord use the following command: /pwnbox init. It will ask for the public key you just copied.
Connect to the work server by following the instructions that marvin sends back
This will provide you with access to a full Linux command-line environment (with many CTF tools preinstalled).
DM Marvin with the slash command /pwnbox remove. Then, you can go through the setup process again with /pwnbox init.
You will often find yourself wanting to edit files on the server. Instead of needing to learn something like Vim, you can use Visual Studio code on your machine to edit files on the remote machine, just as you would locally!
First, you will need to install the official Remote - SSH extension. In the extension tab, search for Remote SSH (it's made by Microsoft) and ensure it's installed. Follow the 6 steps here, and you can edit files on the remote as if they were local files! https://code.visualstudio.com/docs/remote/ssh#_connect-to-a-remote-host
Don't forget to check out the "Linux tips" to get some basics of Linux!