Slacken the barrel adjuster where the cable goes into the mech a half turn at a time. If you have a workstand this adjusting thing is much easier. Don't worry about fine adjusting until you have determined the two screws on the mech are also adjusted correctly. These prevent you from shifting over the top of the cassette into the wheel or off the bottom of it. I have found from experience, if you adjust the shifting on the 2 or 3 smallest sprockets on the cassette, the rest sort of fall into line too.