A - put it into an external enclosure for 2.5" S-ATA HDDs with a USB port (cost 10 € and more), format it correctly (steps shown in second link above), use CarbonCopyCloner to clone the internal HDD to the external SSD, providing it has enough free capacity, swap the HDD with the SSD and start your Mac.
B - put the SSD into the Mac, put the install DVD into the Mac, format it via Disk Utility correctly, install Mac OS X onto, and choose Setup Assistant or Migration Assistant to copy the data you want or use Finder if you want to copy the data from the HDD (in an enclosure like mentioned above) onto your Mac.