Watch the video, then reinforce it by reading the Mt. Κοίνη Grammar
Notice the dropdown in the lower right hand corner. This allows you to vary the way you quiz yourself. Play with it! Take these over and over to drive the lesson home.
It's important to NAIL the alphabet. One great way to do this is to learn to write it. Here's a video of writing the alphabet in the sand. Make yourself write it out. Get used to forming the letters until they become old friends.