A couple of pointers to where to find the appropriate information in the manual:
--Chapter 3, Recording and Editing Patterns (Pattern Edit Mode) - page 52
You can record patterns in one of two modes, realtime recording (page 55) and step recording (page 57). I recommend realtime recording as it is more intuitive. In this mode, the DR-670 continues to loop through the same two measures, and it records anything you touch on the keypad.
--Chapter 4, Recording and Editing Songs (Song Edit Mode) - page 63
Again, you can record songs realtime (by selecting patterns and fills on the fly) or by step recording. In this case I recommend step recording. If you have documented your patterns well, you can assemble a song in step mode in just a couple of minutes.
Good luck!