Go to GT's Ultimate Chord Finder (top right corner of 'old site' page, in "My Guitar Toolbox" page of 'new site'). Click on G major, variation one. What is shown is the common, open G fingering using the 1st, 2nd and 3rd fingers. This is the pattern that Lisa first teaches in her Fundamentals course but a couple tutorials down she uses an alternative pattern.

That alternative pattern uses finger 2 (middle finger) on the 5th string second fret, finger 3 (ring finger) on 6th string third fret, and finger 4 (pinkie) on 1st string third fret. This frees up finger 1 (index finger) for embellishments such as playing 2nd string first fret (adding a C note => a Gsus4 chord). This is the G chord pattern I use regularly although I started a long time ago with the first pattern above. GT lesson Me and Bobby McGee uses this fingering and incorporates the Gsus4 embellishment into the song.

Yet another open G chord pattern I've seen used in GT lessons is the same as the first above except finger 3 (ring) is added and plays the 2nd string third fret (D note), i.e., all four fingers are used making the chord.

I think you'll have the most success, now and later, by learning the fingering patterns that the instructors use. Good luck, have fun!