Thanks, i'm happy you like the rides. It took me a lot of time to get where i am now.
There are 2 different things in your post:
1. Being able to animate exisiting or new rides (like mine)
2. Being able to create your own custom rides
For the first there are already several tutorials available that show the basics of animation. Looking at them will allow you to easily change the animations on my rides or any ride, if that is what you like to do. Just play with the values and keyframes. That's how i learned it too.
For the second is a bit more complicated because you need to know your way with a 3d modeling program like 3ds max. I never used Sketchup and i also do not suggest SU for flat ride models. However SU is a nice and easy way to get fimiliar with 3d modeling.
Having said that, if you like to change anything on my ride and do not know how then drop me line what you like to do and i'll try to explain how to do it.