Extracting information from a school website

I don't know what tools to use for this, but I want to be able to log into a school's website, trigger a javascript command on the page that will expand all of the grades, and extract the grades from the page.

I'm not well versed about web programming, but how would I do this? I'll provide pseudo-code below.

loadWebsite() //www.example.com
enterCredentials() //user, password
sendCredentialsToServer() //post request? don't know too much about it.
loadView() //now user is logged in
expandAllGrades() //all grades will be shown
extractGrades() //retrieve all grades
displayPrettyVersion(grades) //creates a nice infograph and displays it to the user. Use neo4j to display the graph?

I don't own the school's website in any way.

If it helps, this is the javascript code that is executed when I want to expand the grades (grabbed it from google chrome's inspect element).

javascript:submitAction_win0(document.win0,'DERIVED_SAA_DPR_SSS_EXPAND_ALL');

When I want to log in,

submitAction(document.login)