1. Go to CurseForge and find the mod/modpack you wish to install.
2. Once you find the modpack you want to use, under the “Files” section, go to “Additional Files” and download the “Server Files” folder from the options listed.
3. Once you have downloaded the zip file, create a folder on your desktop, extract the files there, and open the installer jar file. Click “Install server”, select the folder you made, and press “OK” to download and save the server files. All server files should now be saved in the folder specified, and should look like the image below:
3. Login to the Modern Hosting Game Panel, and on the console page, "Stop" your server to create a backup. This is in case something goes wrong that requires reverting to a previous state. A tutorial can be found here if you are unfamiliar with this process.
4. Upload the folder you made to your server using SFTP. A tutorial can be found here if you are unfamiliar with this process.
5. In the Game Panel, go to your server, click on “Startup” on the left sidebar, and change the “Server Jar File” and “Minecraft Version” values to match the server file that was uploaded. If you are unfamiliar with this process, please see this article here.
6. In the Game Panel, go to the console page and click on "Start" to turn on your server. The setup process will begin, and all necessary files will be generated. Your server has now been successfully set up to use a Forge modpack.