I want to add that the jacks that come with the cars usually aren't the best. I remember watching some friends of mine have a lot of trouble with the jack because it was too small and difficult to work because of the detachable parts.
I cannot offer much more advice because I have never changed a tire. I used to call my dad when I lived in the same town as him. Now, I would have my husband do it or call AAA. I just know that you need to be careful not to lose any of the small parts. That is my job during the process. *insert joke here about holding nuts*