First of all, welcome to LQ!
Secondly: to install a software in Ubuntu, use the Synaptic package manager. When you open it, press the reload button, so it will download the latest package list. After that press the search button, and type ndiswrapper. It will give some packagege out, like ndiswrapper-common, ndiswrapper-source and ndiswrapper-utils-1.9. To install the packages, click to the little box next to the package names, and select install package. After doing this press the apply button, confirm the selection, and wait. Synaptic will do the rest. After it finishes, the packages will be installed.
About ndiswrapper, I don't know anything, since I never had to use it, so I can't helo you with that. Sorry. Someone else will surely help you. You can also search the forum for existing threads, maybe you will find your answer there. Good luck, and happy Linuxing!