I want to create a simple backing track for practicing a solo. I can record and loop it, but how do I get it to play while I'm practicing my solo? Also, can I activate a simple metronome or should I add a drum arpeggio? Thank you.

You can activate a metronome with various options in Utility > Tempo Setttings > Click

I want to create a simple backing track for practicing a solo. I can record and loop it, but how do I get it to play while I'm practicing my solo? Also, can I activate a simple metronome or should I add a drum arpeggio? Thank you.

If you record it to the MIDI Song Sequencer you can set the LOOP points for Start and End of the Loop
If you record to the Pattern Sequencer the SCENE will repeat automatically. You set the LENGTH to the number of measures you wish to record before recording.

While it plays back - you can SELECT a different PART to play along with it.

Where did you record and loop it?
If you include a Drum Arpeggio when you record and loop it, you will not need a metronome (Click) - many find it much more inspiring to use a Drum Arp as opposed to just a Click. Both are available.

@Cheri....

Assuming everything is done on the MODX (no external DAW, Sequencer, Audio device etc).

If you already have a "roughed out" backing track recorded for solo practicing*, you get it to Play Back on demand by using the Transport Buttons to the immediate low-left of the Screen. The triangle shaped ( > ) button is "Play". The square shaped ( ■ ) is Stop.

* If you recorded either an "Audio" (Audio output only), a "MIDI" or a "Pattern", one hopes that you remembered to touch the screen button "Store Song & Perf Settings" or "Store Pattern & Perf Settings" in the respective Play/Rec menu screens.

This links (permanently associates) the recorded Audio File (.wav for "Audio" Songs) or the Midi File (.mid file for MIDI Songs or Pattern Sequences) to the Performance.

The "chain link" icon in the top centre of the respective Play/Rec screen will turn solid BLUE if the Link/Association was successful. A blue link means that whenever you return to and select that Performance, the MODX will load that Performance AND its associated .wav or .mid file. The .wav and .mid files are stored separately from the Performance Data.

EDIT: If you didn't use the "Store Song & Perf Settings" touchscreen button, don't worry. Whatever you recorded is still in the MODX, just not linked to the Perfirmance. You can LOAD the relevant .wav or .mid file back in from the relevant PLAY/REC screen. It will likely be called something like NewSong07 or NewPattern12 etc.