Hey @psgamergal, sorry for the delay, you should be able to simply subscribe to any mods you'd like using the workshop. Click on a mod that you'd like and you'll see a 'Subscribe' green button near the display picture, above the mods description.
On your Library, when you've selected this game, you will see the a tab that is named 'Workshop'. Click on this to enter the workshop. Once subscribed, a mod will install itself, you do not need to do anything else.
Just remember, mods can be added but mods are difficult if not impossible to remove from an on going game. While mods of this game are extremely stable nowadays consider testing mods to ensure you like them before committing. Some mods have dependencies and require other mods to work, if you see a pop-up when subscribing requesting you subscribe to another mod, please ensure you do so.

Let me know if you have any further issues.