There are a number of tournaments for national teams. If your players play in these matches they can get extra experience.
Each continent has its own qualification tournament for the world cup. The teams are divided in groups of 4 to 6 teams who play each other once at home and once away. After the first round, teams may qualify directly for the world cup or qualify through a home-and-away playoffs with another team from their continent.
In the first tournament the host participated in the qualifications, but in future world and continental cups the host will not participate but directly qualify for the final tournament.
32 countries qualify for the final tournament, held in the break between seasons. In the first round there are 8 groups of 4 teams. The best two teams from each group qualify for the knockout stage in which a single match is played to decide who advances to the next round. Teams from the same group can't meet each other before the finals.
There is one match each day so the matches follow each other quickly. The matches are held at fixed times, starting from 13:00 UTC.
The world cup is held in a host country. The matches of each round are divided over 8 of the biggest stadiums in the country. These stadiums are selected randomly each round, starting with the biggest level in the host country and continuing down until 8 stadiums are selected.
The draw for the group stage is made in week 42. The tournament is played from week 47 till week 1. If your players are selected for this tournament you will NOT be able to use them until their country is eliminated. If you need to participate in the league playoffs you'll have to do so without your world cup players.
The hosts for the World Cup and Continental Championship are drawn based on the number of stadiums in each country. To have a chance to host the world cup a country needs at least 16 level 4 stadiums. For continental championships 8 (for europe), 4 (for oceania and south america) or 6 level 4 stadiums are required.
The more level 4 stadiums a country has the bigger the chance they will be selected as host. Higher level stadiums increase the chance even more.
The World Cup will rotate between Europe and the rest of the world, so one year it's held in Europe and the next in one of the other continents. Also, no country can be selected as host that recently already hosted a national team tournament. For the world cup and european championships, any host of the last 40 seasons is excluded. For other continents this number is lower because there are less candidates in these continents.
New hosts are drawn 8 seasons in advance, 2 weeks after the finals.
The first continental championships (european, asian etc) will be held in season 6. The qualification tournaments will start shortly after the world cup finishes and take two seasons.
The qualification tournaments will be similar to the world cup qualification tournaments. Europe, Africa, Asia and North America will have a 16 team tournament with a group stage followed by knockout rounds. South America and Oceania will have a 5 team tournament where each team plays each other team once.
Week 3,7,15,19,35,47,49 and 51 are reserved for international matches. Countries will usually play one international friendly on these days and may also play an official match.
International friendlies are scheduled a few weeks in advance. Countries that qualified for the world cup or european championship etc. will not play friendly matches.
International friendlies: 400xp, first 3 matches
World cup/Continental qualifiers: 600xp, first 5 matches
Continental championship: 800xp, first 3 matches
World cup: 1000xp, first 3 matches