When your new computer arrives and you start it up for the first time you'll come to a screen called Setup Assistant where you are asked if you'd like to transfer data to the new computer. You answer yes and then you are asked for the source. You'd click on the first choice: From a Mac, TimeMachine backup or startup disk. From there just follow the prompts. See this article for more details.
Important Note: migrating data and applications via WiFi can take a very long time. I mean really long time. If it is at all possible, connect your Mac to the TimeCapsule with an Ethernet cable - the speed increase via giga-ethernet is dramatic!