should i take action?

[Ahmad]

someone has created a twitter account posing to be me. They have my picture and my name. They are tweeting disgusting/embarrassing things about me. could i press charges and how do i go about this.

ps I've already taken screen shots of the page

[Ryan Caltson]

Looking to the Terms of Service of Twitter, it seems you can perfectly take action against such guys.
I've included a link to the terms in the sources.

Know that 'your' picture is also 'your' copyright. Based on that alone you can make a claim, let stand that they're impersonating you. Good luck!