Does anyone know how to do a B to C# trill?

There is no such thing as a B-C# trill because it is not a half step apart. If あなた mean a C-C# trill, then あなた would do the regular C fingering (First finger down on each hand) and the regular C# (Db) fingering (Half-Hole and all fingers down, and middle forked key). I hope this helps! Go oboes!!!!