Welcome to the forum. I'm afraid I don't know anything about simulation, but I wanted to let you know you might have a better chance of getting help with your question if you move the discussion to the Simulation section of the forum. No need to start a new one, just click on "Move discussion" in the Actions box at top right.
Also, since you're a new forum member, you might want to check this discussion: https://forum.solidworks.com/thread/39793. It has some information to help you get the most out of it.
If you are using the advisor, it sounds like you are using full simulation vs sim xpress. So with the addin enabled and a part open, you should have access to more tutorials. Some on weldments and beams.
If you are new to simulation, I would recommend taking a simulation class with your reseller. If that isn't convenient, at hawk ridges we offer online classes sim and also classes where we focus on your problem.
I would also suggest starting a little smaller. Just get a cantilever beam to work. Then add another member...and so on.
I suspect part of the problem is that you're trying to get all the welds and trims into the model. With weldments/beam analysis, you don't include them. If you want that, you'll go with solids.