Welcome to the forum!
Every Lionel item has a number on it. If it is postwar, then go here to help identify it by the numbers.
http://www.tandem-associates.com/lionel/lionel_trains_master_index.htmThe best way to get an idea of your trains' worth is to visit online auction sites.
If there is a Lionel dealer nearby they may be able to help you also.
Larry