Step 1: Install the Modpack on your server
You can automatically install all the mods in a Modpack by setting your server software to it.
ATL Modpacks on Aternos: https://aternos.org/software/modpacks/atl
Step 2: Install the ATLauncher on your PC
ATL: http://atlauncher.com/downloads
Note: ATL will automatically install in the folder that you start it from so it's recommended to move it to a different Folder first. If you want to be able to start it from your desktop rightclick it and select send to > desktop.
After installing it you will need to login to your Minecraft account.
Step 3: Install the Modpack on your PC
Select the Pack and click "New Instance". Aternos doesn't use Optional Mods so don't tick any of these.
Some optional Mods might still work(Map mods, FPS boosters etc.).
Step 4: Start the Pack
Go to the Instances Tab and click Play.
Step 5: Start your Server
After the Game is fully started go back to the website and start the Server.
Starting a modded Server can take a lot longer then starting a normal Server.
Step 6: Connect to your server
If you have problems connecting to your server, you can read our article about that here.
If you want a Modpack to be added to the Modpack list, you can request it on the forums (https://board.aternos.org/).
Before you request anything, you should read this article: https://board.aternos.org/index.php?thread/7366-how-to-write-a-good-plugin-modpack-mod-request/