Adding a border to a knitted babuy afghan

I am a fairly new knitter. I have made a baby afghan with a ridge pattern border on top and bottom of afghan. Now I need to add a ridge pattern to the sides. In order to get 34" afghan I have 235 stitches along the edge. Pattern says to pickup 162 stitches and work in ridge pattern. Can I use all 235 stitches? If not how do I condense 235 stitches to 162 stitches evenly?

Thank you for your help.

I’m not sure what stitch pattern you’re using for the body of the afghan but you could just divide the side into quarters and mark the quarter with scrap yarn or safety pins. Pick up 40sts in section one, 41sts i section 2, 40sts in section 3 and 40 ats in section 4. That will give you a total of 162sts along the side. Basically, you’re picking up about 2 sts for every 3 rows.
There’s a good video under the tips section of Free Videos for picking up sts if you need to see an example.

You don’t pick up in every stitch - a stitch is longer than it is wide so if you picked up every st on the side it would be too ruffley. This looks like you pick up about 2 sts in every 3, so pick up in two sts, skip the next one, pick up in the next 2, skip on, and so on.