First, one does not need the kernel source code to install ndiswrapper, you do need to have the kernel-devel and kernel-headers rpm packages however. Install the freshrpms-release package;
rpm -ivh http://ftp.freshrpms.net/pub/freshrp....fc.noarch.rpm
Or download it then install; http://zod.freshrpms.net/rpm.html?id=118
rpm -ivh freshrpms-release-1.1-1.fc.noarch.rpm
When done as root type: yum install dkms-ndiswrapper
If you have a working Internet connection then the command above should install the additional packages required. if not as i already said you need to have install the kernel-devel and kernel-headers rpm packages for your running kernel along with the dkms rpm package.
Second, the kernel source you downloaded from kernel.org will not work as you intend. The fine folks at Fedora typically make changes (enhancements, tweaks and other 'improvements'). If you want the full kernel source for Fedora then you need to get the source rpm file from them;
You can build a working kernel using the source you downloaded from kernel.org the instructions are here;
The file lkn_pdf.tar.bz2 is what you want to get and review, the short instructions are after downloading and expanding the kernel source are;
The 'make oldconfig' and 'make menuconfig' steps configure and verify that the kernel will build for your hardware correctly. Do take the time while using 'make menuconfig' to insure all your hardware is configured and to make any adjustments required.