Image enlargement in photoshop 7

The first question you've asked would take a full lesson to answer completely. If you select Image > Image Size and then choose the method that works best for the type of image you have. You can try each option, only enlarging as much as you need, and choose Undo to go back to what you started with and then try a different option. Perhaps try only enlarging the image a little and stop when it becomes too grainy.

As to 'special text design,' I have no idea what you're asking. What is it you're having problems with? The interface for text in Photoshop is different than most software, but editing text is possible. I'd suggest using the help menu and learning the basics, since the commands operate so differently in Photoshop.