Unreal means that the condition will not be met, did not happen, or that it is very unlikely to happen.

When to use each kind of conditional

For generalities, you should use a present real conditional.

For plans that have requirements or possible setbacks, use a future real conditional.

For wishes, dreams, and speculation that is doubtful use a present/future unreal conditional.

For regrets, things you'd like to have done differently, and any past events you want to change (but you can't since you're still working on that time machine!) use a past unreal conditional.

Where is past real?

Well there is no past real tense because no matter how much Doctor Who we watch... The TARDIS is not going to materialize on your street corner. We can't go back and change the past. If we could, we would, but we can't so we won't. :-)

Punctuation

The punctuation of conditionals really isn't complicated.

First like any sentence, you'll need a period(.), exclaimation point (!), or question mark( ?) at the end.

The special punctuation is true of any sentence with an adverb clause. If the dependent adverb clause is before the independent clause, you need to put a comma after the adverb clause. If the independent clause is before the adverb clause, then there is no comma.

Dependent, Independent.

or

Independent Dependent.