i just buyed a SSD today and im going to make that as a Main
so my question is my Hard Drive with all the windows Files can i make that into a D: Drive With out Reformating???
You can change the drive letter in Disk Management. If it's been a while since you've reinstalled I assume lots, if not all programs are going to be looking for the files on the old drive letter.
What I'd do is simply clone the old drive to the new SSD and format the hard drive and give it the next letter available, which I assume is D. Be sure to enable/disable all the relevant stuff in WIndows if you're changing from a regular spinning disk drive to a newer solid state disk. Some people simply recommend starting fresh if you're moving to a new SSD.
I usually like to take a new drive as a fresh install time (especially if you're transitioning from HDD -> SSD), but you may want to clone as @BlackHawk indicated. If you do that, there won't be anything special you need to do for the old disk regarding disk letters, programs, etc. Steam can be told about the old install locations if you want to leave them on the old drive though, to avoid complete reinstall (as an example).
Like @Tushon - I see the SSD as a perfect opportunity to clean install Windows. A clone of the old drive may be effective, but without seeing the install I can't tell how messy it is. Installing clean, going through the trouble of figuring out what is going to live on your SSD vs. your platter drive, while it will be more work can be very rewarding once it is set up properly. How much data did you have on your hard drive? How large of an SSD did you purchase?