shaping back neck

does anyone know how to shape back neck without a pattern?

i am knitting a sweater in flat pieces, my gauge is 3 stitches and 4 rows per inch and im using stockinette stitch. my total stitch number for the back piece is 58 stitches.

the shape of the neck i want is a round neck.
can anyone please help me?
thanks a lot in advance

There need not be too much shaping for the back neck. Sometimes it’s just a couple of rows for a round neck. Usually knit across to some number of center sts, bind off or place them on a holder, knit across the second shoulder. After another row or so, put the shoulder sts on a holder. There may or may not be a decrease on those extra rows after the center bind off, maybe one or two sts to shape.
Take a look at some patterns on Ravelry to see exactly what I mean.