Download GIMP <http://www.gimp.org>
Downlaod the LOMO script.
Open up image, run the LOMO script, and... voila! Your images look like it was done with a Lomo. I use this when I shoot with my P&S digital and I want the image to look "bad".
I am one of those unfortunate souls without Lomo experience. To cause vignetting take a piece of black material with a hole in it and hold it in front of the lens. The amount of vignetting will be dependent on the diaphram size, the distance focussed upon, the size of the hole in the material and the distance the material is from the lens front. If you make a hole in a piece of shiny material...say aluminum foil..and do this you will probably also get lens flare.
It is very unfortunate that your newly acquired camera is not working properly.
sorry, but it seems you've got a fake Lomo! May be it was Leicas revenge on the fake Leicas from Russia! Claire has got some good ideas, while not very stylish. Imagine, what would Vivian Westwood do? She might take an empty (maybe not empty) toilet paper roll, adjust the diametre, add some cloth to the outside cut it to a crazy shape - and you would own a Lomo a la carte!