Honestly just download it and install it. Most 3d software is rediculously intimidating for beginners and really hard to grasp but sketchup is super easy, I may write sone brief tutorials though.
I'm just learning as I go and when I get stuck I just look it up. Things do get pretty frustrating when toy get into complex curved surfaces and the like but the software isn't really geared for that. Interior stuff like this is fine though.