Follow the link above and then log in (if you already have a Google account of some kind) or create a Google account (if you don't already have one). Any Google account will allow you to log in. Use the Add a Site button to add your site to the Webmaster account. You can add multiple sites to one account.
Select the option to "Add a meta tag to your site's home page" and then copy the provided tag.
Go within the editor of your site to Settings > Search Engine Optimization and paste the full code into the Header box in this section. Then be sure to Save and Publish your site. If there's already code in the header, put this code above or below it.
You'll now be on the Dashboard page. From here, you submit your site's sitemap. Sitemaps are automatically created for sites on Easy DIY Website at http://website.com/sitemap.xml. Either way, you just need to enter sitemap.xml into the box Google provides you when you submit.
Google Webmaster Tools has a lot of cool features to play around with after you're verified. These features can help you see how well your site is ranked You never have to use them (verification is the only significantly important thing to do here), but they're there if you want to check them out.