So...
I'm a beginner and I've a diatonic harmonica in the key of B...This is a real problem to start because a good part of the songs I've found is in the key of C...
Which songs should i try to play...in B?
Thank you...

Play any tab as written on your harp. The melody will be right, but the pitch will be higher or lower if it's not tabbed for B.

I can't ever remember coming across any song written in B, anyone know of any?

I understood you could play the tags (numbers) for any song in any key of harmonica. I normally use a "C" harp, but bought a "G" harp to better play songs which use holes 8-10 (which are a bit squeaky on "C" harps). Obviously the tone is different, but it plays "C" songs just as well as the "C" harp. Best just give it a try, and if you don't like the sound, then get a "C" harp.

You can also play in third position. Third position on a B harp is C. This might sound very complicated to the beginner, but forget about positions and numberings, all you have to do is use 4 draw as your root note instead of 4 blow. You can easily transcript tabs by simply moving all the numbers up a value.

Four blow becomes four draw, four draw becomes 5 blow, 5 blow becomes 5 draw, etc.

Third position on a B harp is Dd.
Third position on a Bb harp is C.

Yeah, what was I thinking?