To get to the badges, click the blue square on the learntomod homepage. That will take you to the badge index page. Scroll down and you'll see the 'player interact' badges.
However, I recommend completing all the skills and drills: vox-l badges at the top of the page first -- there are about 100+ badges in that category. Basically, anything outside of the skills and drills section is more advanced -- when you've completed an advanced level badge, you'll need to scroll to the bottom of the badge instructions and then press the skip simulator button. Then you can test it in minecraft. You'll be able to test skills and drills vox-l badges within the browser (in the vox-l simulator)