A seventh flat nine chord is created by adding a flattened 9th degree to any dominant 7th chord. E.g. a C7b9 chord contains the notes C, E, G, Bb and Db(1,3, 5, b7 and b9). Here are some common moveable seventh flat 9 chord shapes. Once you know these shapes, transpose them to all keys.
7b9 chords are commonly substituted for dominant 7ths.