Credit cards can be used to buy things.
Seriously, just use it. Pay it occasionally. With Amex, you'll want to hold off on making payments until just before your first statement closing date since they sometimes will only accept one payment before the first statement. After that, use it and pay it down as often as you like. Try to keep your statement balance as low as you can, but above zero. After 61 days get a CLI to $3K. Get the signup bonus. Take a trip with your SkyMiles.
@Anonymouswrote:With Amex credit cards, the best to do is always pay in full and never carry any balance over. People who carry balance on Amex credit cards are known to get adverse actions from them.
But in terms of paying in full, it pretty much means that you pay at least the amount of balance showing on statement X by the due date prior to statement X+1. This way you don't have to pay interest, and it's not considered as carrying a balance over billing periods. It is usually not necessary to pay the new purchases prior to statement cuts, unless you are running close to your credit limit.
For utilization and scoring, you may pre-pay so your statement balance shows up as 1% - 10% of your credit limit, it can be higher but try to be < 28% at statement cut and the lower the better (better not be at $0 unless you got another open revolving account with a balance), mid-cycle balance usually doesn't really matter much.
FWIW, I’ve carried a balance for a couple months with them, we’ll se how it goes on Tuesday with the CLI. I haven’t gotten any “adverse action” the balance was only about 45% of my CL.
Use it/enjoy it/and in my humble option, Pay In Full. 
Appreciate all the "insight" 