You set it to how fast you wanna go and then it should start. If you wanna play to 60bmp, then set it to the number 60. 180bmp to 180. Etc. It's that simple.
Turn it on, let's say 100 BPM. For every Beat, you have to play a certain amount of notes, let's say 4. That would mean you are playing 16th notes.

*click*                *click*                 *click*
     1   2   3   4          1   2   3   4          1   2   3   4  

On the click, you play the first note, followed by the 3 other notes. Be accurate, play the notes evenly spaced apart. If you're not, slow it down to a more comfortable speed.