From Our In-Built Version Installer:
1
First Step
Log in to your Wepwawet Control Panel

2
Second Step
Select your server.

3
Third Step
Make sure to Turn OFF the Server

4
Fourth Step
Create a Backup of the Server
If you don’t know how to make a backup, Here’s our article on How to make a backup

5
Fifth Step
Under the Minecraft section, Click on the Mods tab.

6
Sixth Step
Search for your mod, Select your Provider, Select your Version and then select your Server software

7
Seventh Step
Finally, You can head to the Console tab and Start the server.

There you go! You have installed a Mod on your server!