Credit is basically borrowing someone else's money, and then paying them back plus interest (the fee you pay for the use of their money). Without a long credit history, no sane creditor will give you an intial high-limit credit card. You wouldn't loan a large sum of money to a stranger, so don't expect someone to loan you money if you haven't shown yourself to be trustworthy.
To get a high-limit credit card will take time, patience, and planning. Most credit card companies will give you a low-limit credit card, usually either $250 or $500. Make sure the card is active; use it every month and pay it off. After a couple of months, request an increase. Eventually, your limit will increase. Even if you don't request an increase, they should increase it every few months anyway.
What is it that you want? Is it something you can get a loan for, such as a computer or vehicle? Putting a large amount on your credit card so that it is maxed out will hurt your score (they look at the debt to limit ratio, usually you'll only want to use 30% to 40% of your max limit). Getting a credit card to max it out is a bad decision for someone who is starting off.
As the other user mentioned before, you can become an authorized signer on another card. However, last time I checked, they have been changing it so that authorized signers can't increase their credit score that way. Alot of kids would be able to boost their credit rating by being added to their parents' cards...the creditors are aware of this and have been working to rectify the problem.
Most people should have an average of 2-4 credit cards. Perhaps consider getting 2 low-limit credit cards and spacing out the charges on each card. Most places will allow you to split a charge between two cards.