Does anyone know where I could find a website with a tutorial about adding scenery to my own custom parks? I'm not that good with this stuff, but I would like to add gardens and other things to my park to look more visually appealing.

You might try RCTCompo's Knowledge Base. They've got a few articles that might help you out. There are a few others out there that I can't seem to remember where they are, but there are a couple of tutorial lists at RCT2.com that I know of. You might also want to check out their tutorial forum.

Thanks for your reply, Nforce. But I have already checked RCTCompetition.com, though I have found the tutorial about theming design around rides very helpful, but I am looking more about scenery placement and design more in general in a custom park. RCT2.com (which I have also looked through already a while ago) seems to be down for the moment. But I will go through the tutorials again to see when it is back up.