The following link may provide some ideas for you:
http://www.thortrains.net
Good luck,
Wayne
Modeling HO Freelance Logging Railroad.
Welcome,
The Link provided by Wayne is "terrific and specific", for an "under the bed" layout. You can see what you need to add to what is in the "package". You can add the structures, one at a time, and know exactly where they will be placed. I especially like the first O Scale layout shown. For an 8 year old, this will keep him (and you) happy and busy. A lockable pull down front lip will prevent damage when the layout is "under the bed". Besides your Hobby Shop, you will find that "Layout Flea Markets" are both inspirational and a good source of cheap ready-made scale structures. Incidentally, if you plan to Post pictures on this Forum, you must use Photobucket as the Host. The last of the four options (beginning with [IMG] is the one to use. It will momentarilly say,"Copied". Click in Ctrl V and the "lengthy code" will appear. You then add text and click on Post. There are many of us "Old Timers", who are more than willing to offer advice. Bob