PAST TENSES

Hello,

What is the difference between the past tenses? i.e. past simple,past continuous and past perfect.

Also, which tenses will these sentences belong to:
1. I used to drive. (i think its past simple?)
2. I usually drive. (i think its present simple?)
3. I'm used to driving. (don't know!)

Please help,
Many Thanks.
Sam
UK