To record a track simply press the "Start" button on the top menu bar. This will start drawing a blue line on the main map along your current route.
To pause, or end the current track, press the "Stop" button on the top menu. This will bring up a pop-up menu with the option to "Pause", "Stop and Save", and "Stop and Discard". The "Pause" option will stop recording your track and it will turn off the GPS on the device if you put the app to sleep or switch to another app. The "Stop and Save" option will save the current track to your phone and discard your waypoints. The "Stop and Discard" will end the current track and discard all of the current waypoints.
Waypoints can be added at anytime during a track, as well as an imported or save route from the History tab.