Use the magic wand tool to select the white, then hit the delete button. Note that if your background layer isn’t transparent this won’t work! If it’s not, make a new, transparent layer and put it below the layer with your image. If your original layer is locked then you’ll have to unlock it to do this. Now I always forget how to unlock layers, so I I’d just hit apple(or ctrl)-j to copy that layer and delete the original locked one. :) Clearly I use a lot of cheating in photoshop because I never really learned the proper way to use it, I’m mainly self-taught when it comes to things like this that aren’t just photo editing. :) But it works!