I think there will probably be a video on here showing how to pick up stitches, it's best if you can see it as it makes sense more when you can see it! What you need to do is insert your needle through the first stitch on the right hand side of the top row with the right side facing (back AND front of the stitch if possible, so that you have two strands of yarn over the needle; this makes your picking up more secure) and treat that just like a normal stitch. Wrap the yarn around, pull it through and then you are ready for the next stitch.
You need to work out where you would need to take stitches from to get the 28 stitches evenly across the row. Pick up the next stitch in the same way, and so on.