So I've been trying to learn this game but there are not a lot of resources that I have found, so I'm asking for help, hopefully for the last time.

Here are the things I just don't know:

1:  I keep downloading signs and billboards with nothing on them but the game logo.  How do I put my own images on these?  

2:  Where do I put 'textures'?

3:  How do you build inside portions of dark rides?

I think that's it.  Now it's back to pouring over all the amazing objects I downloaded but have no idea how to use.

Thank you in advance for any links or help you may have to offer.  I wish I could reciprocate, but that ain't gonna be possible for at least a few months.

There's a folder for images in your RCT3 files somewhere, I'd check both the directory under your documents and the other under Frontier Developments as well. I can't grab the exact directory for you because I don't have RCT3 on my computer.

Not sure what you mean by textures, but if you can modify textures there's probably a spot for them in one of the aforementioned locations.

Usually when someone builds a dark ride they place it inside of a large structure, I'm no expert on this, but it'll probably be easiest to theme the layout first and build the structure last.