If you're looking for a decent background, the one below is from the official Dolphins site. Google images also has a lot of good ones.
You can get cutouts of players from the official site as well. The player images in the team section, just click on the player profile and right click on the image of the player and click on Save Image As if you're using Firefox. Not sure the process for other browsers.
If you want better text dafont.com has a lot of good ones.
YouTube tutorials are a god send. Especially when it comes to learning how to cutout players from images.
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