Need help coding google chrome extension.

Hey. I am COMPLETLY new at javascript. I have however coded in visual basic so I understand the basics of javascript.
I have watched a few videos on javascript and networking... but I can't claimb i learn anything from them. So i need your help.

The chrome extension I'm going to make (I say "I'm" but it's really 95% others, 5% me), is probably not that hard for those of you with a little knowledge about JS.

So here it is:
When the user navigates to this webpage https://www.itslearning.com/elogin/d...CustomerId=195 the chrome extension should automaticly press the "Hald fram" button.
It's name: name="ctl00$tbSamlContinue"
It's Id: id="ctl00_tbSamlContinue"

This will cause the webbrowser to navigate to this page: https://idp.feide.no/simplesaml/modu...2Fdefault.aspx

On this page, the extension should auto fill the two textboxes. Id of the first "username", Id of the second "password".
It should fill in the password and username that the user has saved. (I do not know how to save settings in chrome extensions, but i found this https://developer.chrome.com/extensions/options.html).

Then it should finish by pressing the "Logg inn" button, wich is name and Id-less. (Pressing this button in VB looks like this:)

Code:

---

                Dim allelements As HtmlElementCollection = WebBrowser1.Document.All
                For Each webpageelement As HtmlElement In allelements
                    If webpageelement.GetAttribute("value") = "Logg inn" Then
                        webpageelement.InvokeMember("click")
                    End If
                Next

---

I'm not asking you to MAKE it for me. Just help me get the coding started. I'm litterally clueless on what to type.
I've been downloading chrome extensions and looking at their coding to see if I found anything useful :P I didn't

Thanks in advance.