To go from concert pitch (C) to instrument pitch (Bb) all you have to do is go up one full step or two half steps. [two half steps is the same but it helps you not forget that there's only a half step between E F and B C]
Concert Bb is C major on bass clarinet because C is one full step (two half steps) up from Bb. It's really that simple.
F = G
Bb = C
Eb = F
Ab = Bb
Db = Eb
Gb = Ab
G = A
D = E
A = B
E = F# (remember a full step, E - F is a half step, F- F# is another, E-F# is a full step)
B = C# (same deal as E-F#. We usually play Db instead of C#, sounds the same but easier notes to remember)
Now, that part is simple. It works that way for every scale going from concert pitch to Bb instruments (clarinet, trumpet, tenor sax, baritone TC, etc...) -- it's different for other instruments that are in Eb or F.
What notes to play? Also much easier than most young musicians are taught. Don't waste your time trying to learn some magical shortcut or to memorize each scale by rote as though they're all different. All scales are the same.
Major scales. There are only 12. There are also only 12 major key signatures. Memorize the 12 major key signatures (not the notes of each scale) and you'll know ever major scale. For example, F major has one flat, it's Bb. Start on F and play with one flat and you have an F major scale. F G A Bb C D E F -- it's really that simple.
So, if you are asked for Db concert scale. First go up a full step (because your instrument is in Bb) to Eb. Then, Eb major has 3 flats (Bb Eb Ab) [the flats and sharps are always in the same order] so Db concert/Eb major for you is Eb F G Ab Bb C D Eb -- yep, really that easy.
F concert is your G major. G major has one sharp (F#) so is G A B C D E F# G
is a nice chart with all of the key signatures on it. Memorize those (major only to start with) and then just remember that whenever you're asked for a "concert scale" you go up on full step and if you're asked for a "major scale" you play what is asked for.
note: the order of flats is B E A D G C F and the order of sharps is exactly the opposite F C G D A E B. The same orders as the circle in that link.