Welcome to the site Cecil! The lessons are great, and you can also ask the instructors questions, but you have to be patient as sometimes it takes a while for them to answer. To "apply yourself", make some goals, then move directly towards them. So for instance, if your goal is to have a better general understanding of the guitar, go through the fundamentals courses. But if you want to simply learn a specific song, and that's what makes you happy & motivated to practice, then just go for that (you can always do both if you have the time). Take some time out each day, even if its just for 2 minutes, to just experiment without self-judgement and use what you know to come up with your own ideas.

Good luck!