That's a very broad question whose answer would rely on a lot of variables. Such as:
=> What platform is your site on/coded? GoCentral, WordPress, HTML, other?
=> What type of products and how many are you going to sell? One-off, Services, multiple variables, drop-ship?
=> What is your current site's URL (so we can see what you already have in place)?
The above would give us the basic info needed to point you in the right direction.
"Good things happen to those who hustle." ~ Anaïs Nin