If you truly want to learn poker and become a good player, I recommend starting with cash games. It is the most pure form of poker, and once you know how to play cash games well, you have a solid foundation for moving into tournaments.
However if you simply enjoy tournaments much more, there is nothing to wrong with just forgetting cash games and going in that direction. You will probably not master the early phase of tournaments very well, but to some extend that can be solved by playing tight or even by showing up late.
For the tournament route I recommend starting with SnGs to get experience with final table and short handed play before moving into large field MTTs. For me the 45-180 man SnGs on
pokerstars are an absolutely perfect place to start.