Is It Suitable For My Clothing Online Shop?

Hi, I'm the kind of merchant who decided to host my own shopping cart. In other words, I am responsible for securing my server and software against data theft. But then, my issue here is, the person who used to maintain the security of my website was not really efficient in doing his job. I want my business to be safe. Anyone here who could explain to me the process of accepting online credit card payments or payments through a virtual terminal? What is an online payment gateaway? A friend mentioned it to me. Is it suitable for my clothing online shop? :confused: