Step 1:
Navigate to your game panel by clicking "Login to Control Panel".
Step 2:
When you've arrived on your game panel, click "Configuration Files".
Step 3:
Then click on "Text Editor" on the line that's titled "Saved\adminlist.txt".
Step 4:
Simply get your Steam 64 ID, using this website: https://steamid.xyz/
Step 5:
Input your Steam 64 ID found in the previous task and paste it here:
Please note, you can add as many Steam 64 IDs as you want, simply go to the next line and add the next.