OK I’ll try to explain it.
Top Eleven is played across many servers (no idea how many) and each has its own pool of teams from level 1 up to usually around level 70. You find as has rightly been mentioned earlier that at the higher levels there are fewer active teams so this is why even if you have been playing for the whole 8 years, chances are you are stuck around on the same level with other teams catching up to you to fill a league. At the lower levels there are often several leagues across the same level as there are more active teams but higher up (as in my case Level 56) there may be only one or two leagues. There is no league pyramid, it doesn’t work like that. A league season lasts 26 days. However a full season lasts 28 days as Days 1 & 2 covers the Cup first stage. The idea is to finish in the top 8 to promote to the next level. If you finish in position 9-14 you remain at the same level but again, at higher levels with fewer teams, you may still level up from those positions to fill a server level.
Every level has its own Cup and CL competitions and again, you find sometimes they may have teams from the level above or below in the same competition.
At present there is no international competition where you can manage your country, it is all club based. The only thing that may come close is the Associations competition which occurs each weekend. However you compete with your own club and work together with up to 5 other clubs to try and promote to the highest level (Platinum). You win tokens as you promote having reached a certain number of points over each 4 week season.
That is the basics in a nutshell. There are many complexities which would take me all day to cover. You’ll read about them in the forum. I suggest you read the sticky posts in each section and there are loads of YouTube tutorials out there.
Just remember one thing. This game does not reflect real life football in many ways. It will surprise, irritate and make you laugh (sometimes all at once).
Enjoy.