First , make sure your DVR install the hard drive , without hard drive ,it cannot record and play.
About record: If you want the system to record all the time, you need to set up the record manually. Please go to main menu, you will find "Start Record" / "Stop Record" button, please select "Start Record",after that, you will find a green icon on each channel, the system will record all the time.
If you want to record some hours, please go to DVR's Main Menu - Setup - Schedule to set up schedule recording.
About playback: you can click "Playback" to play back the recording files, or you can go to DVR's Main Menu - Search - Time Search to play back the recording.
Please note: Before recording, please go to DVR's Main Menu - Disk Management to format the hard drive.
Here is the links about how to install and format the hard drive:
how to install hard drive
hard disk format