The most popular mods appear at the top, and you can extend the list with the 'Load More' button. When you’re happy, just download the package and extract the zip somewhere and run 'modapi.exe' to run the program.
You just tell the program where to find your game, enable the mods in the menu, and it’ll patch it with the new files.
If you want to add more mods, you can download them from their specific mod page on ModAPI and add them to 'mods' > 'TheForest' folder.