Here is a very clear and detailed crib sheet that should help you. It gives the rule, the example and the explanation.

http://grammar.ccc.commnet.edu/grammar/conditional2.htm

if this is how you are learning English, you have my sympathy

If I had enough money, I would send you to live with an English-speaking family. (Second conditional)>

2
1
1
3
2
3

There is “zero” which is ALWAYS true.
1st is not true yet, but can happen LATER (if I see your sister, I’ll give her the money).
2nd is not true NOW, but theoretically it could be true. (If I were a rich man…)
3rd was not true IN THE PAST, which is why something else didn’t happen (I would have come if I’d known)

There are also mixed conditionals. For example, I would be rich now, if I’d worked harder in the past, or I would have known what that guy was saying (in the past) if I were Spanish (because I’d always be Spanish in this case).