Brassage is the technical name given to chopping up a sound-file into little 'slices' and redistributing them in some user-defined order. The technique of brassage is found in these other effects: Chunk Munger, Granular Synthesis and Sample Hose. In the case of time-stretching, slices are 'chopped' out in a linear order and redistributed in such a way that the effect is of a 'stretching' in the time.

Each slice is crossfaded with the next to give the effect of smoothness. Due to its simplicity, this effect is fast; at longer stretching times, however, an audible 'buzzing' sound will be apparent.

For a less 'nasty' time stretch, try the Spectral Time Stretch. For loooong time stretches, try Granular Synthesis.

Hold length: The length of each 'slice' you want to remain 'as is' when redistributed. Small values (20-50 ms) are good for a smooth time stretch.
Fade length: The length of the crossfade between each 'slice'. Again, small time values are good for a smooth stretch.
New length: The length of your new sound-file. Can be absolute, or relative to the original sound-file.
Mix to: Tells the effect whether you want the new sound-file to be created in a new channel or a new document.