When first booting the game up as a GM, you'll see the screen be a very minimalistic map view and chat box on the right.


You're going to make your way over to the chat box and look towards the top right of it, where "Workshop" is a clickable option.



After clicking that box, a new one will appear that looks as follows:


To load your assets, click on any of the pre-loaded modules, or download some from the workshop/make your own and you're good to go! All you have to do now is drag and drop from the modules into the play-screen/field.

(This is also where you'll go when you want to import your own custom made assets and upload them to the workshop. Good luck!)