Only about two years late, but this shouldn't be a problem. You just need a cable that goes from the headphone out to your speakers. That would typically be 1/8" or 3.5 mm to two RCA outputs. But some speakers take 1/8 in as well so a straight 1/8 to 1/8 stereo cable would work for those. If your speakers take 1/4 inch input you can also buy a 1/8 stereo to two 1/4 output stereo cable. All these types of adapter cables are available on Amazon.
My AmpliTube 5 Getting Started Playlist on YouTube.