My sister did that by doing some "reverse" tech. I don't have a printer but maybe you could do a google search? I wish I knew how she did it but she said it was really easy and it was a matter of the settings on her printer.
Sorry, printers don't print white. One way around this would be to print on white paper/cardstock, but make the background of your page black and place your white text over it. Then, when you print the printer will print the black background and the letters will appear white because they are an absence of color which shows your original white background. If this doesn't make sense, pm me & I can try & explain it better. Bottom line...printers won't print white onto black paper.
I don't think there are many printers that will do that....I have never heard of any that will. White on a printer is only the absence of any other color, not an actual ink color.
That would be so cool if they came out with white ink!!
Yep, there's no way to do it with a printer other than the "reverse" technique described by Carol. That's why opaque white pigment markers like the one by Sharpie are so hot right now.