a total noob question
Hi Slink, when Peter asked what version of Trainz you were using he meant 2009 or Trainz classic or 2006. When you download assets from the download station they should install automatically and be ready for use without you having to do anything further. Have you tried using the train annd see if it works?
Sometimes though if your options aren't set up for automatically committing the assets after downloading they'll be in the open for edit tab in Content Manager. If you click on this tab and see some assets there with a black spanner and hammer icon then they are waiting to be committed. To do this you just click on each item (or select one and then press Ctrl + A to select all of the items) and then press Ctrl+M and they'll commit and then disappear. This means that they are ready for use.
See how that goes but try the train first. It may just be waiting for you to come and play! And don't feel stupid about asking any question because the manuals aren't really that explanatory and there are a lot of things that can only be found out by watching the forums.
Good luck,
Railwayz.