how to make modal sounding bass??

How do i make a pedal bass for modal sounding tunes???

You can specify a particular bass note by using an inversion:
F/C
D-7/F
etc.
Use the slash key (from the android keyboard) when typing in the chord. If the chord is the same and you want to define a moving bass line with that same chord, you use the invisible chord (looks like a pink blob) for the letter name of the chord, then slash then bass note as normal. Or input it using letter W:
W/G
where the previous chord is played along with the bass note of G.

But if you need a walking bass, it will take a while to define the bass line using inversions for each beat!
So assuming you are not practicing a chordal instrument like guitar or piano and need what might be a typical backing track to play along with (you might be playing sax or trumpet for instance) then you could vary the chord qualities throughout the 'same' modal chord.
For instance, a Cm dorian modal piece could be made up of random Cm chord qualities instead of just using Cm7 throughout.
For example use:
C-7, C-11, C-6, C-9
a measure or two of each (or even within the same measure) changing from one to another randomly. This would give a varied bassline and varied comping (with different voicings.) This would be how a pianist or guitarist would play.

I hope something here helps.

Thank you;)