Hi

Record the MIDI 10 sec sound loop.

then -

1. if you want the loop set to the recorded instrument:
   
   Export the loop as an audio file, eg ogg, for use in a project.
   
   Import the saved audio file into a project and drag the right end of the loop object to the right to repeat as many times as required, note - you may have to adjust the tempo to match the project.
   
   OR -
    
2. if you want to be able to change the instrument/synthesizer
   
   In the Midi Editor select File, Export MIDI and save the loop you have created - note where you save this.
   
   The MIDI loop can now be added to a project, and the synthesizer set up and drag right the end of the loop object to the right to repeat as many times as required.

HTH

John EB