To update your Java to the latest version, visit this page: https://www.java.com/en/download/manual.jsp
If you are having issues, contact us on our forums at http://tekkify.com/help
Type in the modpack name (Tekkify 3) or paste the following url into the search box.
Finally, click Install at the bottom right of the launcher after you select Tekkify 3 from the list on the left. The launcher will handle everything else!