Welcome, 

Many folks on here, myself included, started at an early age, gave up for whatever reason and now coming back to it so your not alone. 

Just north of 60 myself so dont worry about your age. 

As for how to proceed if you feel your still at beginner level then I think it's best you complete the Fundamentals courses. Fundamentals are well fundamental to whatever style you want to play so shore up those skills then move around the site as you wish. Learn to play the music that you enjoy listening to and that will keep you motivated. 

Learn each lesson as best as you can before moving on, but don't feel you have to master it down. It's all a work in progress so don't let yourself get fustrated and bogged down on something you are having trouble with. Move on and keep incorporaing it into your daily routine and if you need to at a later time you can always revisit the lesson. It will seem easier then trust me. The beauty of online lessons is they never go away just because you hit complete. You can take the lessons and courses as many times as you need. The one thing to focus on is have patience and enjoy the journey. 

Good Luck,

Moe