Hi, kovo, welcome to the forum!
There is another forum specifically for toy trains, Lionel, etc., where you can probably get more informed information of building a Lionel layout.
Before you begin building a layout, you will want to ask yourself what KIND of layout you want. Do you want to runs a train in a circle, run more than one train at a time, operate like a real railroad? You need to have some idea of what you want before anyone will be able to offer you information.
How much space do you have to devote to a layout? Are you interested in scenery or operating? Will you have help if you need it?
There are a lot of layout planning books available, some may be at your local library. The magazine Classic Toy Trains is geared towards the larger scales like O gauge. A Google search for "Lionel trains" will turn up lots of interesting places where you can get more information.
Just because there is a forum specifically for toy trains, don't feel that you shouldn't post questions here, too! The guys and gals on this forum are interested in TRAINS of any kind and love to help a fellow modeler and see what other modelers are doing, regardless of scale.
Keep us informed and have fun!
Darrell, quiet...for now