I received a letter from discover showing my credit history I'm only 18 so I know I don't have great credit, this is what it told me "Your Credit Score: L2C 645"
Does that mean that my credit score is 645?
Consider it fantastic if you are just starting out.
Just the fact that you got a credit card, with todays new regulations is impressive.
Now, use it responsibly.
Do not dare carrry balances.
Charge something small like gas or food each month and pay in full when the bill comes in the mail. Not the minimum, not more than the minimum, but in full.
This will build amazing credit with time that will be respected by any future creditor.
Carry balances, and you will pay interest and posibly destroy your credit.
About the score: Don't consider it accurate.
Each agency uses it's own scoring formula, and to top it off they use different tier ranges. Never worry about the score. Worry about the secrets to good credit. Pay that card in full each month.