Saxophones come in various types.
Let's take a closer look at the most common types:
soprano saxophone (in Bb)
tenor saxophone (in Eb)
bariton saxophone (in Bb)
When you want to play along with non-transposing instruments, something has to happen with your notes...
If you have access to the notes as written in C (as for piano, flute. violin) it's an easy trick:
For a soprano or tenor saxophone, more or less same story, only select transposition C to Bb.
Now what if you have a Bb-clarinet part and want to transcribe that for tenor saxophone?
The score below shows the original tune for flute (C-instrument) with the alto-saxophone part (Eb-instrument) below
see also: how to arrange music