A few notes on that pattern:
* It's worked longways, 182 stitches long. The various sections use pattern stitches that have to work out to certain multiples. So it's helpful to count the stitches before starting each new section to make sure you still have 182 stitches.
* To avoid the edging problem I encountered, on the first row of the edging, work (142? 144? Not sure which, 'cause I fudged the shells to make it work) stitches evenly spaced across the short edges instead of 140. One of those numbers will make the rows of Woven Stitch work out correctly. (You need the spaces between the Woven Stitches to equal a multiple of four, or 72 spaces.)
* On the edging, the pattern shows the final row of shells on Row 7, which is a wrong-side row---but the photo shows the shells facing right-side. I think the shells look better done on a right-side row. Just leave out a row of Woven Stitches, or make an extra row.
None of this will make much sense until you actually get to the edging of the afghan---just save these notes and tuck them away with the pattern.