Mediaportal running go to plugins, select video editor.
The default is set to cut edit, just change using the up\down buttons and it will scroll, cut, join then DVR-MS to MPEG, which is one of the way's and has great editing abilities.
Personally i use the cut\join functions mostly to get a single file ready to burn (so you can get rid of anything you do not want, ads etc) especially useful if program recorded is split into 2 seperate files.
Remember the Start\end buttons with the add, when using the cut edit facility are the bits you want to keep, not delete. (too many people have done it wrong way round)
For Burning within MP you need the my BURNER plugin enabled, you do this from MP setup\plugins\My Burner right click and scroll to configuration, there are files to download to get this too work, the links\instructions are in the configuration.
If more info needed, just look under plugins for Video-Editor and My Burner on this site.