Find Route with Custom Public Transportation route

[dityo]

Hello there,

I want to create custom bus route in my city, and i want to know how to get some place using defined bus route.
example : i want to go to X from Z, the output is i have to use bus A from X to Y and use bus B from Y to Z.

the problem is I just dont know where to start. Anyone has suggestion for me?

any help would be appreciated

thank you