I play guitar using this scale....this is C major I think...(I don't know the name...but I follow the number on the music note, and it works. ):

But once I come across with this in one music notes:

as you can see, this is not a normal .1, it has a # sign beside it. How can I play this on my guitar? Thanks...
(*please answer me with more details; I am a guitar beginner, with no musical knowledge. Thanks.)