So, I just started playing guitar about a month ago and I have trouble with key signatures and where to play them. I'm basically reading out of Hal Leonard's books and I don't really understand the D Key Signature and A Key Signature. Everywhere I look I can't really understand any of it. Is there anyone who can just tell me what fret to play the note on?

Read away; it should have everything you need to keep you busy for a while.
R.I.P. My Signature. Lost to us in the great Signature Massacre of 2014.

Quote by Master Foo
“A man who mistakes secrets for knowledge is like a man who, seeking light, hugs a candle so closely that he smothers it and burns his hand.”

Music theory is a very important part of learning the instrument. If you have questions about music theory, or general questions related to techniques, check out the Musician Talk forum and read the stickied threads.