I've made it! I'd be happy to help if I can!
When it says work 3 ridges, they mean knit every row until there are 3 ridges made by knitting garter stitch. So like on the Julie H Levy square (2nd square in the book), it says "Work 3 ridges, inc 28 sts evenly across last (RS) row."
So cast on, and knit a row. Turn your work, and knit a row again. Keep turning and knitting until there are 3 ridges on the right side and increase on the last right side row.
Keep in mind that these "ridges" are only the borders for the squares. They don't have to be precisely correct. Just do them the same for all your squares, so take notes when you start your first square. Cast on the same way, and knit the same number of rows for the squares.
Now, regarding reading the pattern. Each pattern is both written out and charted. Pick which way you like, and use those directions. You don't have to use both the text and the charts.
So again, using Julie's square as an example, after you do the ridges and increase to 76 sts, it says "Beg Charts A and B: Row 1 (WS) K3, work 17 sts [of] Chart A, Chart B over 36 sts, 17 sts Chart A, K3. Cont in pats as established keeping 3 sts each side in garter st...". Refer over to the next page where it says "In other words", and look at the directions for Chart A. Start as you were told, K3 (knit 3 sts), then follow row 1 of Chart A, and only row 1. Then knit row 1 of Chart B (only row 1), and knit row 1 of Chart A again. Knit 3 stitches (these are the garter stitch stitches for the borders), and turn. Row 1 of your square is done.
Continue like this knitting 3 sts for your border, then a row of chart A, a row of chart B, a row of chart A again and K3 for your border.
It helps to place a stitch marker between each change in pattern like K3, place a stitch marker, K row 1 of Chart A, place stitch marker, row 1 of chart B, stitch marker, row 1 of chart A, stitch marker, K3. Do this for ALL the squares because it helps to remind you that when you come to a stitch marker, you need to change to another pattern.
It also helps tremendously to use a row counter for both chart A and chart B since they have a different number of rows. Or a note pad, or however you keep track of rows. I used a red row counter for one, and a blue for the other and just kept track of which was which.
Ok, so you're probably a little overwhelmed right now. Maybe this will help. This afghan still is one of my all time favorite projects. It is very challenging. Some squares are way harder than others. But you will learn techniques that you've never dreamed of, and end up with a breathtaking heirloom afghan. Take one square at a time. Don't think about how many squares there are to make. Just do em one at a time and take your time.
Good luck! Don't hesitate to ask more questions if you need help! Keep them in this thread instead of PM, so it can be a learning tool for anyone who wants to knit this afghan.