You might try looking up "How to Sharpen a Broad Axe" which is the proper term for what you have.
Most broad axes have one bevel so that it can chop straight to a line making sharpening it easier than most pole or two bit axes. It is hard to discuss sharpening in a post, but I will try. The key to getting a super sharp edge is making sure the back of the blade is really flat. In fact you will spend more time getting the back flat then the bevel. Hard to believe huh? But it is true. When the back is absolutely flat, you get a straight line, and then you can make the bevel meet it.
Everyone has their preferred methods...me I am super frugal so I use sandpaper and glass. Glass is very flat, so it is an ideal surface to sharpen on. I use self-adhesive sand paper stuck to the glass starting with coarse paper. By the looks of your axe it looks extremely dull, so I would start with 100 grit and work up. It is going to take awhile, but run the flat part over the steel until the back is shiny straight across. Then start working up in grits. 100, 150, 220, 320, 400, 600, 1200, and 2000 grit, using
water in the higher grits. What you are doing is making the "scratches" in the steel more and more refined. The deeper the scratches the more dull the axe is. However once you get up to 1200 and 2000 grit, it is going to be super polished.
From there you flip the axe over and start on the bevel. Here though you must do one thing: keep the bevel the same. If you try to do this my hand or eye, you will inevitably lift or drop the edge thereby "rolling" it, and by doing that, it is dull. You need to make a consistent bevel hit a perfectly flat back. When you do that, you can literally shave with it. You can use a block of
wood cut to the right bevel to make sure you maintain this consistent bevel.
That axe looks like it is pretty dull straight out of the factory (most are) so it might take some time, but once you realize (1) a flat back, and (2) consistent bevel, and (3) polished steel is what it takes to get something ultra sharp, it will open up a whole new world of woodworking, from framing lumber slicks, to router bits, to hand saws.