The Pattern Browser opens to the left of the step grid.
In the Tracks area in Logic Pro, Control-click the MIDI region, then choose Convert > Convert to Pattern Region.
In Logic Pro for Mac, do either of the following:
In the regions already exist on the track, the pattern loop uses the existing track instrument; if the track is empty, the track uses the patch (including the instrument) saved with the pattern. You can also drag a pattern loop to the empty area below the bottom track.
Download the guides:
Logic Pro User Guide: PDF