What you do is, you increase on the 6th row after the first row you increased on, the 6th row after that one, and so on.
For example, say you increased on row 10.
Then you would increase on row 16 (6 rows after row 10).
Then you would increase on row 22 (6 rows after row 16).
And so on...
As you are doing your increases, just work in stockinette stitch as the pattern indicates
Once you've reached 80 stitches, you will just keep working in stockinette stitch until the sleeve is 18 inches long and then bind off.
Hope that makes sense!