Guitar is a very widely used instrument in contemporary music. This is possibly because the instrument is so versitle while still being relatively easy to learn.
When beginning learning guitar, it is usually better to gain some knowledge of music theory, which begins with definitions and background information.
Notes are different pitches produced, in this context, by pressing down a string within a specific fret.
Chords meanwhile, are combinations of any two notes.
A wide range of songs are made up of just four chords.
One of the best ways to begin learning guitar is to learn songs, because just learning chords with no context does little good when actually attempting to create music further on in a musical career.
"Sink, Florida, Sink" by the band Against Me! is a good song to begin with because it is made up of the simpler chords C major, A minor, G major and F major.