You can submit a form using EITHER GET or POST. Using POST it submits seamlessly, "silently". Using GET it can submit a long URL with details.
When Debugging GET Requests, use a URL Decoder such as this one: http://meyerweb.com/eric/tools/dencoder/ to help you understand the elements that are getting passed there. WHY use a URL Decoder? Really the only key reason is because HTTP URLs translate certain characters like "[" into like "%3" and so on. So you translate those back into human-readable characters.
And keep in mind, you just need to get the GET request to MATCH the other type of request... it just needs to be in the identical format
Great resource to play around with forms: http://www.w3schools.com/html/tryit.asp?filename=tryhtml_form_submit