Beginner what is the server adress?

sorry to be so unclever
owncloud asks me the server adress

but where can i create an owncloud server adress ?
if i have to use a personal server adress, then i have an other difficulty : shall i give the ftp adress ?
my aim is to quit apple cloud, google... in order to have a free solution just to synchronise mys contacts between computers and phones

ownCloud is a software which runs on a server. Sounds like you want to configure the desktop client to run with it, that will mean that you first need a server or access to a server! You can set that one up yourself or user one of the community service providers to start. You can have a look at (admin/admin) in order to see how it looks like.