smiletool map help

Hello I'm new to the community and working on my first game. I'm working on the background of my game. I used the map tool in the smiletool to put down a bunch of grass and rocks. I saved the data as BGSCREEN data and named it BG1, and in the default folder, it's named SC_BG1_L1. Now I just want to load it into my game, but I don't know how.