Are you talking about small photos that you want to scan and increase their size for printing or displaying on a computer? If so, you need to scan them at a very high resolution.
If you have already scanned the photos and now want to increase their size without affecting quality, that can be problematic. There are a number of new plug-ins that allow you to do this. But, there is not much in Elements that will help you "sharpen" a low resolution photo when it is magnified.
If you can give us more specifics about your problem, we may be able to offer more help.