round 1: Start with 8 chain stitches (ch).
Slip stitch at the 1st ch to join and form a chain loop.
round 2: Work another 3 ch.
Double crochet (dc) 15 stitches around by inserting a hook into chain loop every time you crochet a new stitch. Do not worry if it is forming a cup, this will correct itself in the following steps.
Slip stitch at the 1st dc stitch to join.
round 3: Work 3 ch.
Dc around again by working 2 stitches at each gap bellow.
Slip stitch at 1st dc to join.
round 4: work 3ch and dc around like in the round 3.
round 5: Work 3ch and 2dc into the first gap bellow. Skip two gaps bellow and work 3dc into the third gap. Repeat the previous step again. For the square corner work 3 treble crochet (tr) at the third gap (from previous dc), stitch 1ch and work 3tr again into the same gap as the previous one. Repeat the process again with other three edges+corners: work 3dc every third gap, at the corner work 3tr 1ch and 3tr in the same gap. At the end slip stitch at the 1st dc.
Have fun with crochet!