In fact, if you successfully learn a few algebra concepts then you will want to have more. Practice is really important in algebra and you ca not expect to learn everything from online courses or tutorials. You need to go through the concepts and the principles of algebra again and again in order to learn them.
When adding fractions without a common denominator, it is necessary to find a common denominator before adding the numerators. Find two equivalent fractions by determining the least common multiple of the two denominators and using that as the denominator for both fractions.