First of all, I will like to say that mining is a very complex job(at least to set up everything). You will need a huge amount of power on the current difficulty to be able to mine so be sure that you have a very powerful hardware or else do not go for mining. Secondary as you can see there are calculators which can help you predict some earning levels but of course they will change after a month but still you can get the idea. Look for the help on YouTube there are many tutorials from many expert miners. Now if you have any questions regarding mining then search if someone has asked that question on the forum or go to
https://bitcointalk.org/index.php?board=14.0 for mining-related discussions.