Ok im confused by the second diagram on this chart, if im playing in the key of G im supposed to start on the 3rd fret where the root note is, but the diagram makes it look like i start below it im confused if anyone can understand it that would help thanks!

its here http://www.myguitarsolo.com/sc_penta_blues.htm
It doesn't matter where you start and stop.

If you learn the shapes created by the scales, you just need to be aware of where the roots and other intervals are, you should be able to 'feel' the resolution to the G.

randomly play around with the scale and try to feel the resolution.

The second one, is the F# pentatonic major...

That blue note is the blues note, that makes it sound bluesy. Hence it being blue.

You can move that scale any where along the fretboard, and it will end up being the scale of whatever start/root note you play it on.

So if you start that same scale on the third fret, youll get that G major pentatonic (with the blues note of course) that you wanted.