How do I use the imperfect subjunctive in an 'if' statement.

The imperfect subjunctive is paired with a conditional in order to show that the conditional could happen, if the imperfect subjunctive were true. Therefore the imperfect subjunctive is used in order to express unlikeliness or impossibility in a statement.For example, in 'If I was rich, I would buy myself a car' which in Spanish is 'Si fuera rico, me compraría un coche' , the word 'fuera' is the imperfect subjunctive word. In this example, the statement is not impossible - however, it is implied to be unlikely by the presence of the imperfect subjunctive.Impossibility, on the other hand, is shown through the use of the perfect subjunctive of 'haber' and a participle, combined with a conditional of 'haber' and a participle. To use the same example but made impossible; 'If I had been rich, I would have bought myself a car' is translated to 'Si hubiera sido rico, me habría comprado un coche'.N.B. The conditional 'habría' in statements such as this is sometimes replaced by 'hubiera' - this is more common in colloquial speech. It is not incorrect to write it, but I feel that it is easier to retain the meaning in your own head if the two different forms are used.