Newbie to model Trains

I'm 64 years old and have been interested in Model trains for quite some time. When I was very young I had a Lionel train set and remember many hours playing with it. Later in life I was interested in learning more about trains and would like to set up a train system to set up for Christmas for the grand kids. Preferably some sort of portable setup. A couple of years ago I purchased a IHC locomotive and some cars to set up under the tree. Unfortunately the train fell off a table and was destroyed. This year I purchased a Mehano locomotive and discovered the couplings are different than the ones on the cars I already have. That being said I know nothing about the different types and all the things I need to learn about model trains and hope I can learn a lot from the knowledgeable folks on this forum.