"For" would be used to express purpose whereas "to" would be generally used to indicate direction. I am going to my grandmother's house for dinner. My friend went to the movie theater for his birthday. We traveled to the university for a debate between two professors, who were available for an informal discussion at its completion. I hope this makes some sense!

You can find plenty of examples on TheFreeDictionary.com: http://www.thefreedictionary.com/for http://www.thefreedictionary.com/to "To" usually indicates some kind of transit, so we use it with verbs of motion (go to the city), communication (explain to me) and so on. That might help you in deciding which to use. In practice, it's best to find good examples and learn those without analysing them too much.

There are many different ways to use both, but here are some examples: I went to the store. They are going to school. I wish I could go to Disneyland. I have been studying Spanish for five months. I need to buy food for dinner. I went to my parents' house for breakfast. I hope these help.