When I post a picture it says I'm with someone that I'm not with.

Post your picture

Have you tried posting the picture ?

If you posted the picture you can delete it. If someone else posted it you can.t

Preventing someone post a picture of you is almost impossible. But if you spot a picture from you, you don't want on Facebook, you can contact the Facebook Website and ask them to remove the picture. You have to make clear it is you on the picture and you don't want it on the site. Make clear you never allowed anyone to put it there. Could be difficult to prove it is you in the picture, but if you can, you always can claim portrait rights.
Point to article 5 from this page:
https://www.facebook.com/legal/terms

If you post a picture, it would be shown in your wall as well. If you really want to achieve this, ask that 'someone' to post a picture.

I am assuming that you mean that he pictures that have been posted are of you that are now on Facebook? if this is the correct assumption, then here is what to do:

1. with the page in front of you of the picture you are viewing, you need to go to contact support for offensive picture
2. for what reason the picture is offensive, you enlist other and then explain that this photo is of you and that the person did not have your authorization to upload such offensive photo of yourself.
3. if the person that did this is someone you know, then deal with that person one on one, but still report them, they will probably be banned from the site.
4. if the person is not someone you know, then also contact the police department and get this on a police report
5. you can have the attorney that you hire, subpoena Facebook so that they will expose the IP address of the person that did this unlawful act. then with the ip exposed, you can slap a lawsuit on this person for the pain and suffering it has caused. Good luck, best of luck, and let us know how it all turns out!

p.s. if the police tell you that you cannot file a report, tell them they are wrong and here is the link to prove it from many attorneys

Is it illegal for someone to post pictures of you on the internet...

Angie Where on facebook is this picture and what kind of picture is it? If it is on someone else's page all you can do is tag it and say it's offensive and report it. If it's on yours you should be able to delete it or again if someone else posted it you report it as being offensive and report to proper authorities.