Instructions for edging rectangles:
Rnd 1: Join contrasting color with sc in upper right corner, * ch 3, sc in same st, (ch 2, sc) 4 times evenly across end, ending with last sc in next corner; ch 3, sc in same st, (ch 2, sc) 10 times evenly across side, ending with last sc in next corner; repeat from *; ch 3, sc in same st, (ch 2, sc) 3 times evenly across side, ch 2, join with sl st in first sc. You should have 10 ch-2 sps along each long side, 4 ch-2 sps along each end and 4 ch-3 corner sps. Fasten off.
Rnd 2: Join next color with sl st in any corner ch-2 sp, ch 3 (counts as dc), (dc, ch 2, 2 dc) in same sp, * (ch 1, 2 dc in next ch-2 sp) across to corner, ch 1 **, (2 dc, ch 2, 2 dc) in corner; repeat from * around ending last repeat at **, join in top of beginning ch-3. Fasten off.