How do I find beat per minute in a song

I recorded a bunch of audio tracks with Band in a Box.
the track are in time and all the beats work.
But I do not know the Bpm that was used.
I want to add some other instruments with Band in a Box, but I do not know the Bpm to use.
The Grid lines in n_Track to not line up with the tracks - too much space at the beginning or something.
I how can I find the Bpm?

I really don’t know Bax maybe this might help get you there.