Gary has given the best answer to your question I would like to add a few things to it since you did ask "HOW"
You should, of course, move as many Non Program Folders to your D drive. I would set up your new folders in an orderly, easy to find , manner. I would do this.
"Right click" on a blank area of your desk top. Select New>Folder from the drop down menu. Without clicking anything else, type Music.
Right click the desktop again and repeat except name this folder Videos
create as many folders as you have types of files. Ring tones, Photos, etc...
Now drag the files from drive C into the proper folder on your desktop. When you have finished simply open My Computer, open Drive D and drag (or copy/paste) your new folders into the Drive D window. Confirm that the files made the transfer by opening a few of them from the Drive D window. If all went well, delete any copies of these folders that may have remained on your desktop.
For programs, If you have the installation CD's you will need to open Control Panel> Add/Remove Programs. There will be a list of installed programs. Remove any programs that you have the cd and registration codes for. You can also uninstall any free programs that you have . Add a folder to Drive D and name it Program Files
Start reinstalling your programs. During installation you will come to "Destination Folder" and you will see C://Program Files/ followed by the name of the program. Change the C to a D and leave everything else in the line alone. Click next and repeat this for all of your programs which you uninstalled earlier.
Now you should defragment your C Drive. You will find the disc defragmenter by clicking Start> All Programs> Accessories> System Tools
Good luck. You can write me from my profile page should you need any further explanation.