Google is your friend.

One main difference between the two is the length of time. Ser is used for long/infinite time, and Estar is used for temporary time.

For example, "The man is handsome" uses Ser ("el hombre es guapo") because the man's handsomeness is pretty static.

Now, "The book is in the library" uses Estar ("el libro esta en la biblioteca") because the book may not always be in the library.

There are some other rules, like Estar is used when describing locations. I used to have a small card that had the differences in uses on it. I found it at Barnes and Noble for $3. Once I memorized it, gave it to a friend.

P.S. I wish this forum allowed you to type accented vowels.