Can I move my operating system and data from a internal hdd to a ssd.
Yes. You can use a program like Clonezilla or True image to clone the drive over to the SSD. How ever the drive new drive ( The SSD ) must be the same capacity as the old drive or bigger in order to do it.
I meant how do you do it? Do you have to put the computer together with a ssd or what?
This is exactly what u were asking in your thread Data transfer. Why do you keep creating new threads for the same question?
Not really there are programs that can deal with that. O&O Diskimage for instance.