What do F 8 to F 20 coin grades mean ?

I am not a coin collector but I recently got interested in purchasing some Morgan Silver Dollars on ebay. Up until today, I purchased 3 of these coins ( 1 for $ 9.50 + 2 for $ 12.50 each ). Today on ebay I bought a " lot " of 11 of these Morgan Silver Dollars for $ 12.50 for the whole " lot " of 11. The ebay coin dealer " ad " said these were mixed dates & were graded from F 8 to F 20. I can't imagine that I got " ripped of " at that price ?...but I was hoping that a true coin collector could enlighten me as to what I may have purchased with respect to these coins & also guide me as to what I should look for or seek if I purchase any more Morgan Silver Dollars ? Also, I ordered something called " Never Dull Polish " which I understand is okay to use to clean these coins ? I haven't received any of above 14 Morgan dollars or the polish yet; but it has also been suggested that I buy Black Ring Airtite Morgan Holders ? I would welcome any good advice or guidance ?

First of all you never clean coins for they lose their value. How someone could sell a lot of 11 real silver dollars for $12.50 is beyond me for he sure lost a lot of money just in the silver alone. You are playing a dangerous game and in the end will lose your money. The 11 silver dollars have to be fakes. Any coin dealer that tells a collector to clean his coins, may have done so for the coins he sells are cleaned. A $1000 coin harshly cleaned may only be worth a $100 or if an inexpensive coin will only be worth its silver value and loses its collector value. I would need to see the coins or at least scans. You need to learn about grading. Coins are graded on a scale of 1-70 these days but the old designations are still with us. An aver age coin in grade good is called good-4 the next step up is Very Good-8, then Fine- 12, then Very fine 20 and so on up the scale. Instead of writing fine-12 most collectors use F-12. I hate to see new collectors start out wrong and get screwed by so called dealers who are really crooks. If you wish, email me through Yahoo answers and I will send you an email address so we can go over this more. Don't buy any more coins on Ebay.