Conditionals

You can find a complete explaination of conditionals in English at Englishlanguageguide.com.

Here's a small part of what they offer

Structure of Conditional Sentences
The Zero Conditional is used for actions that are always true when the conditions are satisfied. The structure of the conditionals is straightforward. There are two basic possibilities in terms of order in the sentence:

IF	Condition	Result
If	it rains,	we will get wet

Result	IF	Condition
we will get wet	If	it rains,

* Notice that we only use a comma in the first example.

Conditionals: Time and Probability Table

Probability	Conditional	Example	Time
Certain	zero conditional	If you heat water to 100 degrees celsius, it boils	any time
Likely	first conditional	If it rains, I will stay in.	future
Unlikely	second conditional	If I won the lottery, I would retire.	future
Impossible	second conditional	If I had the money, I would lend it to you	present
Impossible	third conditional	If I had seen him, I would have given him the message.	past