Shape shoulder.... help

[knittwo]

Hi Everyone,
This is my first attempt at knitting a sweater. I am up to shaping the shoulder and am confused as to where exactly I am shaping.

Pattern is for a toddler sweater. Pattern is as follows:

Divide for Back Opening
1st Row - K26, turn.
Cont on these 26 sts.
2nd Row - K2, purl to end.
Keeping garter st boarder correct, cont until work measures 40cm from beg, ending with a purl row.

I am ok up to here......

Shape Shoulder
Cast off 5 sts at beg of next row and foll alt row, then 5 sts at beg of foll alt row.
Work 1 row.
Leave rem 11 sts on a stitch holder.

So does that mean that I cast off 5 purlwise (from center of back, at the divide) and purl to end (to armhole side) then knit back to center and cast off another 5 purlwise an purl to end (armhole) then cast off 5 knitwise (from armhole side), knit to center and purl to end (center) ????

I hope I have explained this ok as I am confused :/

Can someone please help to explain this to me step by step please???

Thanks

[suzeeq]

Cast off only at the shoulder edge, not at the neck edge. It says 'at beg of next row and foll alt row'. The 'foll alt row' means 'every other row'.