Method 1(Limited to certain amount of MB)
1. Open the panel and select your desired server
2. Turn off your server and go to the File Manager
3. Delete your already existing world folder on the panel if there is one
4. Zip the world folder you wish to upload using an archiving program(ex: 7zip)
5. On the panel click the upload button and select the zipped folder you wish to upload
6. Once it is uploaded on the panel click on the 3 dots next to it and click unarchive
7. Rename your custom world folder to world (capitalizations matters)
8. Restart your server
Method 2(Not limited)
1. Install an SFTP program(EX:WinSCP, FileZilla)
2. Open the panel and select your desired server
3. Turn off your server and go to the settings tab
4. Click on the 'LAUNCH SFTP' button
5. If the SFTP program asks for your SFTP password then enter the exact same password as the one you have on the panel
6. Right-click on the already existing world folder and click delete
7. Rename your custom world folder to world (capitalization matters)
8. Drag and drop your world folder on the SFTP window
9. Restart your server