Let´s learn how to make crochet ribbing:

Abbreviations: ch: chain, sc: single crochet, sc-tbl: single crochet through the back loop, sl st: slip stitch

Work the chain length desired plus 1, to make this tutorial I will use ch6 but you will use the number of chains you need for your pattern.

Ch6, sc in second chain from crochet hook and 1sc in each of next 5 chains, *(sl st on next st) twice.

Turn your work.

1sc-tbl in each of next 5sc, ch1.

On this picture you can see the back loop of stitch more clear

This is how will loop after your 1sc-tbl in each of next 5sc, ch1.

Turn your work.

1sc-tbl in each of next 5sc.

Repeat from*, until end, sl st.

If you are working in round (ex. hat, socks, cowls, etc), using a tapestry needle sew the edges of ribbing for a clean finishing.