Plug the guitar into the jack labeled "Input" on the front of your amp.
Set up any effects chain that you have and connect a 1/4-inch cable between the "Send" jack on the amp and the "Input" jack on the effect. Any effect that can receive a 1/4-inch cable can be used here; use your imagination.
Connect a 1/4-inch cable between the "Output" jack on the effect chain and the "Return" jack on the back of the amp.
Make sure that the effects are turned on. Play a note on the guitar and then play with the "FX Blend" knob on the front of the amp. Turning the knob clockwise will increase the amount of the effects in the mix; turning it counterclockwise will decrease the amount of the effects. Experiment to find a blend that suits the effect and your guitar playing.