There is plenty of information of this forum, so start by looking at past threads. You did not specify which visa you're interested in. Added to that, no one can tell you how long it will take, as every case is different. If you have more specifid questions go ahead and ask, but otherwise, please look through past posts first.

 

my 2 cents, read immi site, check sticky threads in the forum, gulp down all the info and then come back for more .

wish you luck
PS it might take anything between 6 months to 3 years from start to end.