Front post double crochet
US front-post dc wraps around the post from the front, raising it toward you.
Counted practice swatch
Make a foundation row of 15 dc. Use plain dc in both edge positions and front-post dc in the 13 inner positions.
Work the repeat
Yarn over, insert from front to back beside the post, then back to front on its other side. Pull up a loop around the post; yarn over through two twice.
Read the fabric
The post stitch replaces the dc above that post. For ribbing alternate front- and back-post stitches, preserving the same columns on later rounds.