You want to apply an insertion effect (DSP2, 3 or 4) to the voice part (R1 or R2).
There are lots of DSP to choose from; for a clean echo effect, you want one that's of type DELAY.
For guitar echo, you might want one of the types which combines delay with e.g. distortion.
Once you've selected an effect, you can adjust various parameters e.g. the delay time to your liking,
If you save the voice in a registration, your edited parameters will be saved with it. If you save it as a user voice, they won't. You can save your edited effect as a User Effect though; then if you save as a user voice it will save with a pointer to the user effect.
