Fig. 1: Extended G Major Scale

The root (G) is in parenthesis.  It appears 3 times. The G major scale consists of 7 notes: G, A, B, C, D, E, and F#.  Number them, in order,  from 1-7 and you’ll have your scale steps. The 1st scale step is G. The 2nd is A and so forth.

Fig. 2: G Chord

Here is the G chord played two ways. It’s the 1st, 3rd, and 5th scale steps.

Fig. 3: Gsus2

We get a suspended 2nd chord when we add the 2nd scale step (A) to the G chord triad.    Each measure below begins with the Gsus2 but resolves to a plain G chord.

Fig. 4: Gsus4

If we add the 4th scale step (C)  we end up with a suspended 4th chord.

Fig. 5: G6

By adding the 6th scale step (E) we create a sixth chord or G6.

Fig. 6 Gmaj7

When the 7th scale step (F#) is added to a G chord gives us a G major 7th (Gmaj7, GM7).