Help with pattern / I'm a new knitter

I’m working on the crochet edge cardigan in ecobaby by Debbie Bliss.
Can someone help me decipher the following:

Dec one st at armhole edge on next row and 2 foll right side rows. 55 sts. Cont straight until back measures 10 3/4 in from cast on edge, ending with a wrong side row.

i was thinking about it but i’m a very novice crocheter and have a few knitting projects otn right now…but maybe i’ll take notes and do it at a later date…i’m dying to learn crochet