There is three diffrents rankings in TrackMania² Canyon: the solo ranking, the medals ranking (in solo mode) and the multiplayer ranking.
The ranking is split between two modes: solo and multiplayer but they both work in the same way pretty much. You have to earn points to evolve on the differents rankings: on your department/region (if exists), country, world and group(s). Note that your group ranking is based on your total points in the solo mode or multiplayer mode and not related to the others players of the group.
You earn places on the solo ranking by gaining "skillpoints" (or SP) that you earn when you make official times on the map compaign. More skillpoints you have, more you will be well-placed in the ranking. The gains of skillpoints is calculated on the following method: more people register an official time on a map, more you will earn skillpoint if you make a good official time. For example (non-revelant) if you make a good time on the A01 race you'll earn a lot of skillpoints because this map is played by a lot of players but if you make a very good time on E01 race, you'll earn certainly earn less or the same amount of skillpoints because only few players arrive to finish it.
Yet there is another ranking in solo, the medals one. This one is based of the amount of medals that you've earned during the solo campaign.
The multiplayer ranking has the same presentation that in the solo ranking. You'll see your ranking in the differents areas (department, region, country, world and group(s)) but earning "Ladder Points" (or LP) is different that in the solo mode. To earn Ladder Points you have to play on game servers and try to arrive first compared to others players presents on the server. The amount of Ladder Point earn on each race depend on the ranking of your opponents and yours, you'll gain a lot of Ladder Point if you finish a race ahead another player well placed in the multiplayer ranking but you'll earn few points or even none if you have a very good ranking compared to others players. Moreover the game servers can be playable only if you have enough Ladder Points. For example you can see on the server explorer that servers can ask to have at least 20 000 Ladder Points to be able to play on them (but you could be able to join it as a spectator). But this type of restriction can be inverted, on a server for players between 0 et 50 000 Ladder Points, if you have more than 50 000 you'll not be kicked from the server but you'll not earn Ladder Points on them. The limit of Ladder Points that a player can get is 100 000. From 90 000 Ladder Points, players have to play on the Race Of Champions (ROC) servers only open on Sunday from 15:00 GMT to 18:00 GMT to keep on winning Ladder Points. The RoC servers have to be approved by nadeo and players can ask for having a RoC on the maniaplanet forums.
By playing regurlarly, you'll be able to arrive on the top 100 of your region and even of your country if you play long enough.