You can do it any of several ways. As of version 2010, you can enter the chords directly using Bb changes if you have the Bb fakebook.

Or you can enter the chords in C from the C Realbook and then use the transpose functions to change what you see to play along with a Bb instrument, without changing the pitch.

I play tenor. You probably know this, but just in case, a Bb tenor sax is a transposing instrument, and sounds a ninth lower than written. That's an octave plus a full step. So, if you want a concert C to sound, you play a D on the tenor sax. The horn is pitched a full step "low" so you play a full step "higher" to compensate.

Whatever you want to do with transposition and fakebooks, I'm sure the program can do it, and we can help you with specific questions.

BIAB 2025 Win Audiophile. Software: Studio One 7 Pro, Swam horns, Acoustica-7, Notion 6, Song Master Pro, Win 11 Home. Hardware: Intel i9, 32 Gb; Roland Integra-7, Presonus 192 & Faderport 8, Royer 121, Adam Sub8 & Neumann 120 monitors.