The root

Every scale has a root. This is the basic note that the scale is named after. If you have an A major scale, then then root is A. In scale charts, the root is often indicated in some way. In the scale chart below the root is indicated by a red circle.

You will notice that there are 2 notes that are circled in this scale fingering. That is because there are only so many different notes in any particular scale fingering, before the names of the notes start over. So both of the note that are circled in red have the same note name, they are just an octave apart.

If you take the above scale form, and play it so that the root is an A, you have an A major scale. The 4th string, 5th fret is an A, so that is where you would play this scale. In order to understand what the name of a scale will be when played at different frets, you will need to know what the names of the notes on the neck of the bass are. Especially the 4th and 3rd strings, which all of the basic scale forms that you will learn will be based from.

Page 3, Horizontal scale charts

Page 1, Scale basics