The kind you have chosen is certainly not the most common...
I am myself biased toward the push button chromatic harmonica.
There are several models of harmonica with two rows of 24
holes. This can be a tremolo but also a chord harmonica
or a (tremolo) octave harmonica.
Makers propose them in one, two or several tonalities.
Would be great if you tell us exactly what model it is
as the placement of reeds and a few other things differ.
The most common are in C, starting with a C, a G or even a E.
There is a published method for tremolo by a Phil Duncan. This
could be worth if it covers with examples the kind of music you like.
I have found these sites thanks to Google:
Hope it helps. If you can read german or french, there are
many resources on harmonica in these languages. I know that
there is also a bunch of passionates in Korea and Japan,
and I have been impressed by the proficiency of the most
famous japan harmonicists.
About awe's remark on kissing, cross training with harmonica
playing could definitely be a good idea :-)