If you’re wondering about the online guitar class, there are two ways of looking at the question. One viewpoint says you need to learn musical theory and read sheet music. This method of learning gives any student the maximum number of possibilities. The idea is that you have learned to read music and know your theory, it does not matter how talented, or otherwise, you are, you have the knowledge it takes to get a job in a band or as a session musician or a guitar teacher. More success is obtained with this method if you start early in life.
When you are older, you may not want to learn what all the little dots mean; you want to grab the tabs to some songs, and start playing. You learn to play the music you like. Guitar tabs is an easy method of writing music, and you can learn it in half an hour. Using tabs to learn songs depends on knowing what the music sounds like. Tabs show you where to put your fingers, but not how long the individual notes last, or the time signature and tempo of the song. To make the most of learning from tabs, you should have a YouTube video of someone showing how to play the song, so you can pick up some pointers about guitar playing that tabs can’t show you.
Watching guitarists or guitar teachers on video will help you with how to hold the guitar, the way to place your fingers on the fretboard, and how to strum and pick. If you have any technical questions about guitar playing, you can probably find a video clip on YouTube that solves it. The other way of getting help with your playing is to join a guitar forum like Guitar for Beginners and Beyond
Other areas of music such as improvising and song writing are open to you whether you can read music or not. Someone with grounding in musical theory will probably find it easier because he would be familiar with the way songs are constructed, but if you don’t read music, you can start with whatever material you have. If you have a tune in your head, you can put words to it. If you have words, you can fit them to an existing tune, and change it around a little.
The thing that can put you ahead of a person who has learnt music, is the hours of practice you have under your belt. If you have the time to spend a minimum of two hours a day on your guitar, you will have the intimacy with the chords, scales and songs you have learned that will enable you to develop your own way of writing songs or improvising.
The best way to learn how to play the guitar is the way that involves you making use of every opportunity to learn, any way you can.