How can I make this crocheted hat?

The best thing you can do is search the internet for a pattern of the same or a similar hat. Since you are a beginner, you shouldn't try to make your own pattern or wing it, though I'm sure you will be able to do that once you have some experience under your belt! Once you have a pattern you should have all the information you need such as hook size and the type and amount of yarn you will need. The instructions will tell you what you need to know to work on the hat. If there are abbreviations on the pattern, you can do a quick internet search to find out what that means and most sites will be able to tell you how to execute the specific stitch.