I suggest you start learning how to use variables because you're gonna be pretty much screwed from the get-go when trying to make a CBS if you don't know how to use variables.
What do you mean "Do credits"? You mean, like a screen where you thank everybody that helped you? If so, then just make an image in MSPaint which has all the people you want to thank in and what they did to help. Then just import it and use the "Show Picture" command to make it appear on screen.
If you meant something else then provide a bit more detail, and I'll have spent the last couple of minutes pointlessly typing...XD