I'm using a Capo for the first time and wanted to know if I understand correctly how it works. Right now I have my Capo across the strings on the third fret. By placing it there and using the open C as a reference, if I understand correctly the key I would be in would be 3 half steps higher or D#. So if I had the Capo on the fourth fret, the key would be 4 half steps higher than C which is E. Do I have this correct or have I got it wrong? Thanks
Playing that open C shape gives you - 1st fret - C#, 2nd fret - D, 3rd fret - Eb, 4th fret E, 5th fret - F, 6th fret - F#, 7th fret - G, 8th fret - G#/Ab, 9th fret - A, 10th fret - Bb and 11th fret - B (if you can reach it!). I've named the chords by their most common names.
To help you, make a circle like a clock face, (12 points), and write each note name in order round it. Counting round is simpler.