The first thing you want to do before routing FX is make sure you have sufficiently sent audio through the main output of your mixer through an input channel. The instructions for this can be found on this article here. For our illustrations, we are using channel 1 on the mixer:
After this, you then want to follow the below instructions.
Routing the FX bus
1. Press the FX A button in the Mix Select section to access settings for the FX A mix. The faders move to show FX A send levels for each channel in your mix.
2. For each channel that you wish to send to FX A, move the related fader to the desired level. Increasing the fader level increase how processed, or “wet”, any given channel will sound.
Make sure to also bring the mix "Master" fader to Unity at this time.
3. Select the FX processor you want to use at this time with the drop down menu. Note that FX A and B may already be defaulted to a simple Reverb that should be heard for our purposes.
4. Press the "Main Mix" button.
Make sure you are looking at the inputs area of the mixer at this time:
5. Press the "Next" button until you reveal the final page showing the "FX Return" faders.
6. Begin to turn up the FX Return Fader for the mix you create. Note that as expressed in the level setting procedures, if you are using channel 1 as described, the Return Fader should be the last thing necessary in order to hear FX out of the Main output.
7. Using the Fat Channel after selecting the Return Fader channel, you can apply Compression and EQ to the FX A Output. This can help quell unwanted resonances and make the effected signal sound more polished.