I would advise you to move your x-cart to the root file as noted above. Seek professional help if you are not capable of this yourself.

However, if there are good reasons for to keep your x-cart in a sub folder there is another route you could take. Keep everything where it is at, but build your index.html page to mirror the design of your x-cart and use static links and images to send customers and SEs deep into your x-cart. This way you can use the static pages for SEO and send your customers to your cart to buy.