I think the op meant installing an SSD on a system with Windows 7 installed already
If you want to clone your Windows 7 from HDD to SSD, use Acronis True Image or other imaging software. I recommend using CCleaner software to clean your system first. As well as disable hibernation to save amount of data written to SSD during clone.
After cloning with Acronis, you change boot order in BIOS to use your SSD first. Then unplug your HDD to make sure it can boot into your windows. Then you can format your HDD and do what you what.