• Click on your modpack card, at the home-screen.
• Close the screen, and click on ➕ Install Content.
• Here, you can search and add all your desired mods, data packs, shaders, and resource-packs!
  • Data packs won't work automatically. All the datapacks will be saved in the datapacks folder.

• Click on your modpack card, at the home-screen.
• Click on ⚙️ Options.
• Scroll all the way down and click on 🔒 Unlock.

• Navigate back to the ⬜ Contents section, and click on 🔍 Add Content.
• Here, you can search and add all your desired mods, data packs, shaders, and resource-packs!
  • Data packs won't work automatically. All the datapacks will be saved in the datapacks folder.

• Select your modpack card.
• Click on the Edit button, on the sidebar.
• A new window will open. Select Mods on the tab list, then click on Download Mods.
• Search for your desired mod.
• Select the mod and click on Select mod for download.
• Click on Review and confirm.
• A window will appear, click Ok.

The same steps can be repeated for adding resource-packs and shaders.

• You can add mods by clicking on the Add Mods button, below your OptimumFuse instance.
• Here, you can add all your desired mods, shaders, and resource-packs!

As always, refer to your launcher's documentation.