As Adriatic said, there is a learning curve to SCARM and I wouldn't expect you to pick it up the first day. However, you should be able to download the SCARM file and at least open it in SCARM. To download the file, you need to right-click on the filename and use the Save As option to save it on your computer and then you might have to change the file extension from txt to scarm.
Anyway, I've been trying to get close to what I think you layout looks like today, so here's what I've come up with. The pink/purple tracks are the grades to the bridge. The yellow bridge is at 5" elevation and as you can see, the grade up is 5.1% and the grade down is 3.7%. Unfortunately, that makes the inner oval fairly small and tight. In addition to the bridge, I added the tunnels and 2 buildings. The track centers are 4.5" from the edge of the decking and the centers of the tracks on the left in the tunnel are also 4.5" apart. I'm not sure how the fire station will fit in. The inner circle can't be any smaller it and the crossovers can't be moved to the right without increasing the 5.1% grade or lowering the bridge height. If you lower the bridge to only 3", then you can move things over by 2 of the 10" tracks and get the grade down to 3.9%. I didn't replace some of the 10" tracks with 30" tracks until you decide what you want to do with the bridge height, so the parts list is not accurate yet.