Train's screen captures are from one of his systems, to show you how he has it set up.

Step 10 from Midknyte's link has the instructions on how to remove the existing partitions from the C: drive (with the D: drive disconnected), and reformat the C: drive.

If you disconnect the D: drive, boot from the Windows 7 install CD/DVD, and follow the instructions in step 10 from Midknyte's link, you should be on your way to reformatting the C: drive and performins a clean install of Windows 7.