That's great. Have any photos or more details? How big and how deep are the pipes buried?
4" pipe has always been sufficient and it doesn't have to be buried deeply since it'll only carry water when its raining. About 6" below grade is sufficient and keep in mind that eventually the pipe will surface. Use the pipe with holes and face those downward.
Against the house either trench or box in an area of sufficient size to collect roof run-off. The pipe is buried under the gravel and directly on top of an impermeable liner, either 6mm black plastic or epdm pond liner. The idea is to catch and hold the water here until its moved off by the pipe. You definitely don't want water hanging out around your foundation.
Of utmost importance is getting the drainage correct so employ a level.
I don't have any pictures to share but I can draw a diagram if that will help. If you have any other questions don't hesitate.