web service json twitter

I'm trying to make an application to search a profile on twitter through a Json web service, I'm looking in the official twitter api uri to show the profile of a specific user. I use this:

  

link

     

(Example of official documentation)

But I get the following error:

  

{"errors": [{"code": 215, "message": "Bad Authentication data."}]}

I do not know if it is the right uri or if I need to do something else.