Probably not, but maybe, to a limited extent, you can soon.
This is specific to the United States of America, as it's the law I'm familiar with. If you're doing business in another country, the details about copyright expiration dates and fair use will vary.
This is all as of 2021, but I'll note expected changes in 2022 and 2024.
As of 2021, almost everything Winnie the Pooh related is still protected by copyright. Is is possible to commercially use something protected by someone else's copyright, but if you're just decorating something, probably not. The details of what you can do are Fair Use law, which is complex, nuanced, and potentially irrelevant if the copyright holder's lawyers have enough money to bankrupt you. To very crudely summarize, the closer your work is to non-profit, transformative, academic commentary that uses a small amount of the material and doesn't compete with the original, the more likely it is to be Fair Use. But it's super fuzzy. (And if anyone tells you that "the four factors" represent some sort of easy to interpret test, they don't understand the law in question.)
As background, Winnie the Pooh was created by A. A. Milne, originally in the poem "Teddy Bear" from his collection When We Were Very Young, where Pooh is named Edward Bear. Edward was illustrated in that and later books by Ernest Shepard. In the first book of Pooh stories, Winnie the Pooh, Milne notes that Christopher Robin has renamed Edward Bear to Winnie-the-Pooh. The relevant publication dates are:
|"Teddy Bear" (in When We Were Very Young)
|Winnie the Pooh
|The House at Pooh Corner
|"Winnie the Pooh and the Honey Tree"
||Walt Disney Productions
Edward Bear originally appears in A.A. Milne's "Teddy Bear" in his poem collection When We Were Very Young. We don't get a lot of description beyond "short and fat." It does include illustrations by Ernest Shepard. That entire book is out of copyright in the United States (and, I believe most of the work). That is to say, they're now in the public domain and you can use the text and illustrations as you like. Note that the illustrations in question and black and white line drawings. Any color versions you find were created later and have a later copyright expiration date.
As of 2021 you are limited to Milne's 1924 words (so it's Edward Bear, not Winnie the Pooh) and Shepard's 1924 black-and-white line drawings (so no color and is distinct from the Disney popularized design).
As of 2022, Winnie the Pooh's copyright expires. At that point the words and art in that book will be fair game. Again, no color, and use Shepard's style through 1926, not Disney's later style. But, you can call the bear Winnie the Pooh!
But... Disney has a trademark on the name "Winnie the Pooh." You can still use it, but if Disney can successfully convince a court that you've confused customers into thinking you sell Official Disney Winnie the Pooh products, you're doomed. Definitely do not title anything you create "Winnie the Pooh"; beyond that, good luck.
As of 2024 both of Milne's short story collections about Pooh, and the art Shepard provided, will be public domain.
But Disney's design doesn't expire until at least 2061. Disney's first Pooh short film is 1966, and in many ways the public idea of Winnie the Pooh is dominated by Disney's interpretation. Disney's Pooh looks similar, but is different. The coloration is, I believe, entirely Disney's creation. If you go anywhere near Disney's design you're at high risk. That design won't enter the public domain until 2061, and even then you're at risk until Disney's later works all expire.
Some cursory research suggests that Winnie the Pooh's copyright might last a few years longer in Great Britain. The United States copyright durations are longer than many countries; so depending on where you are, it's possibly it's already in the public domain. On the other hand, the United States is trying to get other countries to sign on to longer durations. And it's always possible that the United States will extend its own durations again, but it's practically impossible before 2022 and unlikely to happen by 2024.
(I expect it's much too late for my answer to be useful to the original querent, but as I stumbled across this while researching Pooh copyright expiration dates for myself, I figure it might be useful to others on a similar search.)