That looks like algae to me. Step one is to order one of our recommended test kits, either the TF-100 or the Taylor K2006C so that we can get some reliable readings upon which to make further recommendations. We simply do not trust pool store testing.
The second step is to add enough liquid chlorine, aka bleach, to raise your FC by 5 ppm. Do this each day to keep things from getting any worse until your test kit arrives. You can use the Pool Math app to determine how much bleach to add for your pool size.
Once your kit arrives post a full range of tests here and we can make recommendations to help you get that cleared up. In the meantime, visit our Pool School page to learn more about the TFP method and especially pay attention to the SLAM process because you are going to have to do that.