ok i want to get something online, that in a week will be sold out for 3 months they said. It is 50 bucks and i need my moms credit card. She is on vacation right now and left her wallet at home. If i pay for this using her credit card, how will the bill look like and how do i pay for it without her knowing. But i will pay for it with my own money so can someone tell me how to do this

Go to the store and get a prepaid Visa or Mastercard. They are available at most places, even grocery stores and convenience stores carry them. You can pay cash to get a card that is worth $50 and then use the card to buy your item online.