On the BitInstant site, it says that I can trade in my paper money at places like CVS, 7-11 and Walmart and get bitcoins sent to me in the next 30 minutes. Can some explain how this works and what I have to do. Do I just go up to the clerk a 7-11 and hand him my invoice i recieved at BitInstant.com and I will get my bitcoins?
BitInstant has teamed up with an already-existing payment processor. This payment processor is designed to allow those without credit cards make purchases online. The way it works is that you make your purchases, check out, and a special receipt is generated with a transaction ID. At this point the transaction is in a "pending" state, awaiting payment. You take that receipt to a participating location (thousands worldwide), they check the transaction ID from the receipt and your cash and then finalize the transaction.
Purchasing bitcoins via BitInstant is really no different, except that your "cart" contains Bitcoins.
Any place with a "Money Gram" red telephone is what you need. Simple as picking up the phone and following directions on the sheet you printed. You must use your real name and ID however.