I have this site here: http://msdn.microsoft.com/en-us/library/jj164022(v=office.15).aspx
the text in some part says: The following JavaScript code demonstrates how to make this GET request that returns a JSON representation of all of a site’s lists by using JQuery. It also assumes that you have a valid OAuth access token that is stored in the accessToken variable. You do not need the access token if you make this call from inside an app web, as you would in a SharePoint-hosted app.
jQuery.ajax({
url: http:// site url/_api/web/lists,
type: "GET",
headers: {
"ACCEPT","application/json;odata=verbose",
"Authorization", "Bearer " + accessToken
},
})
the specific question is how can I get the access token??