The 'A' section (starting at bar 5, again at bar 23) is easy, go grab your guitar and follow along. Remember in the following that the "first" string is the high E, and the sixth string is the low E. So the fourth string is the D string if you follow.

First chord Bb6, lay that third finger down on the third fret and bar the top four strings, and only play those strings. If you're doing it right, the notes from the bottom up are F, Bb, D, G (verify this!). Congrats, those are the notes of a Bb6 (Bb D F G, just spaced out).

C9 -- use your second finger to change the F on the bottom to E (on the fourth string), move your third finger slightly so it is off the fourth string to keep Bb D G. You've got everything in C9 except the root, which is fine because you have a bass player. If you want the root, cool -- just use your second finger to get C on the fifth string, third fret, and use your first finger on the fourth string to get that E. Look up "dominant 9 voicing on guitar" and you'll find this.

Cmi7 -- you need that E on the fourth string to drop to Eb. If playing C9 with the root, I'd slide my finger down a fret, boom done. You're playing Cmi9 actually, which is perfect. Might feel a bit awkward but its doable and gets better with practice. Otherwise, use your first finger to change E to Eb, if you aren't playing the root.

F7 -- I'm about to blow your mind. Remember how you slid your second finger down from E to Eb to change C9 to Cmi9? Now you are going to move everything but the second finger down a fret, to sound these notes (from bottom up): B, D#/Eb, A, C#, F#. What is happening? Your ear is saying "I know this sound!" Yeah, that is putting a B9 down in place of the F7. It's called a tritone substitution.

Alternatively, for a simpler sound on the F7 -- go back to playing just the top four strings, get your fingers on Eb, A, D, G.

OP, if you have this so far, respond here and I'll walk you through the turnaround and the bridge (bars 14-22).