I need someone to integrate a new payment method in my website

My website is currently in need of a payment system integration, and I am looking for someone who can make this happen in a week’s time. Although I am not sure what type of payment system to use, I ideally need advice on what the best method to choose is, while still keeping the integrity of my website intact. I am open to using PayPal or Stripe as the payment system, or another specified option that would be the most suitable. Furthermore, I am unsure if there is already an existing payment system setup on my website or if this will be the first system, so I could use advice on that as well. Please let me know if you are able to provide assistance in this project and I look forward to hearing back soon!