How do I purchase Bitcoins? Way too complex. Give me an actual example as to how this works? For example; 

How do I purchase bitcoins?
How much do they cost; is there an exchange rate?
How do I redeem them; turn them back into dollars?
A complex subject with an array of different possibilities results in answers of the same nature. If we provide simple answers, it won't be very helpful. For example:

Q: How do I purchase bitcoins?
A: Depends.

Q: How much do they cost?
A: Depends.

Q: Is there an exchange rate?
A: Yes.

Q: How do I redeem them; turn them back into dollars?
A: Depends. 

Complex yet more helpful answers:

Q: How do I purchase bitcoins?
A: Depends on where you live, but I think it's safe to assume you are in the United States based on the details your questions. Coinbase and Circle are US friendly sites that will sell you bitcoins after your sign up and provide them with your personal and financials information. Or you can use a service like localbitcoins to find someone nearby that will meet you at a public place that will sell you bitcoins for your cold-hard cash. Or you can try to find a bitcoin ATM, that will turn your cash into bitcoins. The last two options will require you to have a bitcoin wallet, whereas coinbase and circle can also act as your wallet. 

Q: How much do they cost?
A: Depends where you buy them from. Some places are more expensive than others.

Q: Is there an exchange rate?
A: Yes, there are many different exchanges resulting in many different exchange rates. See here http://bitcoincharts.com/markets/currency/USD.html

Q: How do I redeem them; turn them back into dollars?
A: Depends. If you use coinbase or circle they have an option for you to 'sell' your bitcoins back to them and they will ACH deposit the funds back to your bank account in dollars. Or you can find a person on localbitcoins and sell to an individual.