The programming tab shown at the bottom of the rendering above (which can be cut off after flashing for minimal final board size!) can be connected to a PIC programmer (such as a PICkit or ICD) via a Tag-Connect cable. The Tag-Connect cable should be a 6-pin no-legs variant such as this one that connects to a PICkit 3. A retention clip for the no-leg Tag-connect connector makes life very easy. Lastly, if you lose your retention clips, you might want to invest in a state-of-the-art-and-absolutely-not-just-a-paperclip retention clip holder.