Here is a little trick to help you remember how many days are in each month. Hold out your hands in front of you, palm down, and make a fist. Now, look at your knuckles and the valleys in between them. Start with the left most knuckle and call it January, the valley adjacent to it is February, the next knuckle is March and so on down to December which is the second to last knuckle on your right hand. The spot between your two hands does not count as a valley. Since each knuckle is a high spot, it represents 31 days. Each valley is a low spot and therefore represents 30 days. The only exception is February, which has 28 days (29 in a leap year). You probably know this, but you can remember it because February is the little valley next to your little finger, so it is the smallest.
Another way to remember the number of days in each month is with the following rhyme, which you have probably heard, but have probably not remembered.
Thirty days hath September,
April, June, and November;
All the rest have thirty-one,
Except with February alone,
And that has twenty-eight days clear,
And twenty-nine in each leap year.