You can't "stretch" a partition using XP alone, it has no facility to do this.
The need a partition manager, something like partition magic (try the CD's on the front of computer mags, you may find a free one)
But!!!
There is a very real danger that you will destroy the C partition and everything on it in streaching the partition.
If I was you I would recreate the partition you just deleted and learn to use the "extra" drive this will create on your computer (it's easy to move your documents folder to it for example)