It isn't all that hard realy. When you form a clan first you try to find some players to join yours. Whenever you ahve a few members you can challenge other clans into a battle. Every battle ... lets say between two clans with both 4 players play 8 matches. The clan with the most points after all 8 matches are finished (1 point per win) wins the challenge and the entire 8 points are added to your score.
As a clanleader You alone can challenge other clans. You could either just send in a challenge and see if the other clanleader accepts the challange. If (s)he does you have to make a line-up for the matches i.e. which player of you clan plays which opponent. The thing is you can't see the line-up of the other clan ... so it is possible that your top player ends up playing the lowest ranked player of the other clan. Sometimes that is good clan tactics... usually clanleaders contact eachother before the challenge and discuss the line-up. In that way you can line-up evenly matched challenges.
Every member likes to play a certain number of players. At the " members info" page (for clanleaders only) you can see how many matches every member would like to play and how many they are playing right now. This is the total of all matches, noty just the clan matches.
Basicly thats the job. You can make it as lively as you like. I like to inform the clan players of our progres in the charts, welcome new members, et cetera ... its a fun job really.
I hope I have made things a bit more clear for you. Good luck in creating your own clan .. or, you could always join mine of course