You can type the word "store" for example somewhere in your page where you think it will be seen the best and then create a link to the Zen Cart's index page or it's home page in other words.

You would type the address as follows: "http://www.yourdomain.com/zencart/index.htm" making sure to substitute "yourdomain" for yours and "zencart" for the name of the folder the store is in and the "index.htm" for the name of the page the store opens to. Could be index.php or .htm or .html

If you can pm me a link to the store, I'll be able to give you a better description.