Start by going online to your state's DOH webpage. Somewhere on there should be a link to EMS, from where you can find classes offered in your area (it takes some seaching, but you should be able to find it).
As far as length goes, it depends on how often your class meets- state protocols require a base number of contact hours, so it depends on how the instructor spreads it out. Mine met 2-3 nights a week for 3 hours each night and ran for four months and I'm helping teach a class that meets 3 hours a session twice a week for 5.5 months. I know of classes in the area that are as short as 3.5, and as long as 7 months.
Specifics of material covered depends on state and local protocols (for example some regions of our state basics can push activated charcoal, but we can't, so we're not taught the material to the same degree they are). But every class covers "the basics:"
-vital signs
-CPR
-communications and documentation
-airway management/breathing assistance, oxygen administration
-bleeding control
-splinting/backboarding, KED use and extrication
-patient assessment (both medical and trauma)
-basic pharmacology (this will be the area of greatest difference between states- it depends on what you're allowed to do)
-specific diseases- cardiac and respiratory related, diabetes, strokes, seizures, allergic reactions, etc,
-childbirth
-and then specifics of how things are different for pediatric/geriatric patients
Hope this helps. And enjoy!