Bottom line likes stated: if you are going to design a site, learn how to do basic HTML coding.
The problem with the resolution is most likely you are using fixed widths beyond the scope of a standard layout and not using a liquid design. If you set fixed widths they really need to be viewable by people all the way down to 800x600 as that is still a viable user market.
If you are concerned then design around liquid layouts. Do a Google search on this and you will find thousands of how-to's. Spend some time learning and your problem will solve itself.