Q: I'd like to get any info on how should I act not to violate design rights.

A: Football logos are protected by trademark law. Trademark protection is recognized in the first user of the logo to associate the logo with good or services in a marketplace. The protection of that logo is automatic, but limited. For a larger set of legal protections, the logo owner should register the trademark in the federal registration system (part of the US Patent and Trademark Office). There are state-level trademark laws, but they are likely not your main concern.

All major NFL teams have protected their team names, logos, and branding with federal trademark registration. There are two major parts of this protection; unless you hold official rights (called a "license") to that team name, logo, or branding, you cannot (1) use that logo or branding on any goods or services restricted in the trademark registration, and (2) use that logo or branding in any way that is likely to cause confusion in the marketplace. The confusion this law references is confusion about the identity of the seller of the goods. If the public might be confused that your NFL-themed goods are actually sold by the NFL team itself, then you cannot use that logo or branding.

Take a look at the registration for a particular sports team in Baltimore. Look up federal trademark serial number 76035798. It is protected in four classes of commerce: one class for posters, trading cards, stickers, and memorabilia; one class for clothing like printed t-shirts; one class for toys, stuffed animals, and footballs; and one class for "arranging and conducting athletic competitions, namely, professional football games and exhibitions." This may sound like you could use the same log for a different purpose, like a brand of food or a brand of paint. But even if you avoid direct infringement on these protected cases of commerce, the use of a common and recognizable logo will create the likelihood of confusion problem mentioned earlier. This rule is well established in a court case called In re E. I. du Pont de Nemours & Co, 476 F.2d 1357 (1973). A similar case involving Shell Oil 992 F.2d at 1207 (1989) stated "If the [trade]marks of the respective parties are identical or virtually identical, the relationship between the goods and/or services need not be as close to support a finding of likelihood of confusion as would be required if there were differences between the marks."

That is why the use of the same logo or a close look-alike logo borrowed from an NFL team cannot be used on your picture frames. The USPTO protects the registered trademark against likelihood of confusion about the actual source of the goods. Without a license from the trademark holder, your picture frames are limited to artistry that is not likely to make anyone in the public think the goods are a product sold by the NFL team itself.