Can someone give an understandable synopsis of all the soccer leagues and how they work MLS FIFA UEFa Champions Leagues English Premiere and more how do they all work together?

The Barclays English Premier League (EPL) is a league consisting of 20 teams who each play each other twice in a season. At the end of the year, the bottom three teams are relegated to the Championship. The top two teams in the Championship take their places, and the teams that finish in places 3rd, 4th, 5th, 6th play each other and the winner occupies the final place.

I believe the MLS orks in pretty much the same fashion.

The Champions league consists of about 8 groups of 4 teams who are seeded ( like in each group there will be a team like Barcelona, one like Schalke, one like Atalanta and then one nobody has ever heard of before) The top two from each group go through, and from there its a straight knockout competiton, but the third placed team in the group stages goes into the Europa League, and the bottom group goes home.