The fretboard diagram above shows the first position of a major pentatonic scale. This is the position in which the root is the lowest note of the scale you can play. Find the root of the scale on the fourth string and put your second finger on that fret. In this position, the root of the scale can also be played on the second string with your fourth finger.
Notice the symmetrical shape the notes of the scale make. On the left is a line of three notes and a fourth one fret higher, and on the right is the same shape rotated 180 degrees. Remembering these shapes is a great way to memorize the fingering patterns.