If you’re starting modding Stardew Valley, you need to start here with the Stardew Valley Wiki Player’s Guide to Getting Mods

I also suggest following Salamence on YouTube for a good resource.

If you want to an easier way to organize/download your Stardew Valley mods, I suggest using Vortex Mod Manager.

If you’re trying to install Stardew Valley Expanded for the first time, I suggest following this guide .