I don't have your particular amp, but usually they all work the same with regards to tuners.
Basically, after plugging into your amp as normal, you plug another normal instrument cable into the tuner out socket and into the input jack of whichever tuner you have and always leave the tuner in the 'on' position. The tuner output jack is just a copy of your amp's input signal, in other words: your bass. You are basically connecting this copy of what the amp receives at its instrument input jack to a permanently on tuner (although you could use this output for anything really, like direct recording, to a mixer, to additional amplifiers etc.)
The only downside to this is that while you play the tuner will react to every note you are playing and could be distracting (although this could also be useful if you like checking your bass is in tune while you play, for example if you are playing a fretless and want to check your intonation.)
Also, connecting a pedal tuner in this way means you can no longer just step on it to mute and tune up in silence. So, unless the amplifier has a mute / tuner mute switch on the front panel / by an additional footswitch, the whole operation of tuning up will be broadcast through the amp's speaker!
Hope this helps.