Screw On Lens for Nikon?

I bought a cheap screw-on lens online for my Nikon d5000. What kind of adapter lens do I need to be able to use it?

There are far too many screw-on "lenses" to know unless you tell us which one you have.

Do you know that it does not matter what camera you have, but the lens you are attempting to attach the "lens"

If your lens is a 18-55 mm, then you need an add-on lens with a 52 mm thread. If you bought the wrong one, the already poor quality lens will show more problems, mostly vignetting

Was it a screw-on the front filter "lens", or screw into a T1 adapter lens?

What screw-on lens are you talking about? Is it a semi-fisheye lens adapter that screws on to your existing lens? You should have gotten one with the same filer size as your existing lens. If they have different sizes, get a step-up or step-down filter ring to make the two ends meet. Examples are 52mm-49mm step-down or 58mm-67mm step-up rings. Determine the screw-on thread of the lens adapter and the filter size of your lens to know what to order.

If you are talking about a lens with a screw mount (M42 or T-mount), get an adapter. Examples are "M42 to Canon EF/EOS adapter" and "T-mount adapter for Nikon". Just substitute to your camera's brand/mount.