ok... i'll eplain for ya. You download the trainer to some folder. I use my documents. Most likely it is zipped so you need an unzipping program. Go here and get the demo.
www.winzip.com Once you have it unzipped open rct. once in the game pause it. hold alt and hit tab. It will take you to your desktop. Open my documents and open the trainer. Click on the rct box at bottom to go back into the game. I would recommend you use dragonioa v6. easy to use and works. Any questions, just ask. O yeah and you will need the drexler patch to open asved games.
To coastercrzy: if you continue to have probs... uninstall the game the install it again. Make sure you back up saved tracks and games.