Hello, and welcome!
Thanks for your patience; I see that you posted your question a while ago, and different experts are online at various times. I recently logged in and read your question.
First, you need to sign up for an account with USPS; this is free of charge. Please visit the following webpage to do this:
If you already have an account, just sign in.
After you sign up or sign in, go to 'Quick Tools' where you will see the option to buy stamps and click that, then make your order from there and follow directions to complete your transaction.
I hope this helped!
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