How do you find the key signature of a song?

Question:

How do you find the key signature of a song?

I am writing a song on my guitar and i have a chord progression i made up. how can i tell what they key signatue is? i am so confused with key signatues! i play the piano too and i never have been able to under stand it. if anyone can help me please do!!!

Additional Details

6 months ago
Not time signature, key signature!! the one with all the flats and sharps!

Best Answer - Chosen by Asker: 6 months ago
Not time signature, key signature!! the one with all the flats and sharps!