If the SSD is SAME SIZE or BIGGER than your current HD you can just clone the current HD to it and, when that's ready, put the SSD where the HD is now (keep your old HD unchanged until you're sure all is fine!)
If the SSD is SMALLER then your current HD you might be able to do the same, but then you would have to use a partition tool to shrink the current partition on your HD first. That's easy if the total space used is smaller than the SSD size. If the total space used is bigger you have to delete files (you're own files: documents, music, pictures, movies, etc) until it will fit. Be sure to have 2 backups at least of what you delete and don't want to lose, so you can put it back later.
The alternative is to just install the SSD totally empty and install the OS and all your applications on it, just like you would do on a new hard disk. In principle, you can use the data on your old HD after that, but it won't harm at all to have it fully backed up on an external hard disk before you start.