No, with a few very limited exceptions. The person who created the image (the artist or photographer) owns the copyright and can dictate how the image can or cannot be used. Unless that person is you, or unless you've purchased the copyright from the image creator, then you cannot upload the image to Wikipedia without violating copyright.
The very limited exceptions are images in the public domain (very old photos, for example, or official non-classified works of the U.S. federal government) and images that the creator has explicitly licensed under a free license. In either case, you need to specify where you got the image so that its copyright status can be verified. ("Fair use" is also an option for some images, but it's remarkably narrow in scope and difficult to explain, and it cannot be used on all Wikipedias.)
Copyright law is very complicated, unfortunately, so if you want more detail then you should really talk to a lawyer who specializes in intellectual property law.