There are [at least] two ways to do this. If the amount of data on your current HDD will fit in the formatted space of the SSD (e.g. 111GB for a "120GB" SSD or 238GB for a "256GB" SSD), then you can connect the SSD then use a utility like Acronis True Image to clone the HDD onto the SSD. Then set the SSD in your BIOS as the boot device and test.
Or, you may temporarily remove the HDD, install the SSD, and do a fresh install of Windows on it. Once that is done, re-install the HDD and make sure the SSD is set in your BIOS as the first boot device. You will also need to re-install all your programs.
In either case, the HDD will get a different letter and can thereafter be used for data. You will likely need to answer a UAC prompt from time to time as you take back control of various directories on it.