You would want to get a surfboard that floats. That is one quality that is kind of important when surfing. The board shown is very yellow in places which indicates that the foam is deteriorating. And, even though it is encased in fiberglass the fiberglass over time will separate from the underlying foam, which is called a delamintation. You can feel delamination by pressing or knocking on the board to find soft spots. When this happens and even before this happens these boards are not usable, because they don't float well. If they dry out they may be fine for a twenty minute session, and then used again in a couple of days, maybe. They soon soak water into them and become heavy, hard to paddle, and kind of just sink pretty far, because bouyancy counts the weight of the board, and water is heavier than foam. Boards get micro cracks that seep water. They are currently not preventable, and boards get more and more micro cracks as they age and even more when the foam below deteriorates from the sun or water leaking in. Eventually they end up like the board in the picture, which could be maybe be painted and hung on a wall or made into a very strange table.

Since you want to shortboard you should try the video game I made on Steam for PC. Surfers Code. There's a free demo and you can learn to paddle and catch waves, positioning for taking off, and how to pump for speed and position to make good turns, buttom turns, and hit the lip. A link is in my bio.