Help with a really silly question

Hi everyone. I have a really stupid question. I'll start a campaing here, but i dont know how to put images in my campaing. I pretend play Mutant Year Zero, but i dont know how to share anything.  This is an example. My image map is really big, but when i put on roll20, it stay small like in this print. I dont know how to make my map appear in all screen. Can someone help me please?  Thanks

You're on the right track!  What's happens is you dropped it on the Objects layer, where tokens are intended to go. The default behavior there is to scale things to about a grid square. You need to move it to the map layer (right click it, there's and option in that menu), thrm sekext it and grab the corners to drag it out to a good size.