CiviCRM REST API Call
As kainuk mentioned, you don't have the right syntax for the json field, i needs to be json= instead of json:

http://www.mysite.com/wp-content/plugins/civicrm/civicrm/extern/rest.php?entity=Contact&amp;action=create&amp;api_key=(myAPIkey)&amp;key=(mySiteKey)&amp;json={“contact_type":"Individual","first_name":"Tester","last_name":"Yolanda"}


(it needs to be post, not get for all operations like create that modify the database)

and I would strongly recommend you to do rest over an encrypted connection (https instead of http), otherwise you risk having your keys being read by someone else than civi

X+