E-commerce Transactions (ONLY FOR USA CITIZENS)

I'm in need of help setting up an e-commerce transaction system. This setup will need to easily and securely process up to 100 transactions per month. I'm looking for an experienced and knowledgeable freelancer who can ensure that the transaction system is properly setup for secure, safe, and efficient processing. If you have the necessary skills and confidence in your ability to create a reliable transaction system, then I would be glad to consider working with you.