What nwmalthead22 said.
However, you're going to have to do a partial mash or use amylase enzyme in order to "throw in corn or rice" so that you convert their starches to sugars for fermentation. About 20% by weight total for corn grits + minute rice should do it. That could be mashed (145-148 F - low) with about double that weight of 2-row malted barley. The link in bleme's post above uses Amylase enzyme instead with extract only. Don't hop it very heavy either, almost none, and mostly just for a little bittering.
Another gotcha is that ale yeast is going to make more flavor than a lite lager beer has. You would need to use lager yeast or at least a clean ale yeast like US-05 and ferment in 65-70 F range. Don't let it get out of that range INSIDE the fermenter.
If you are interested in a partial mash recipe that turns out kind of similar to a commercial light lager but with ale yeast, I have done that on a 1/2 gallon scale just as a test and was surprised that it was similar (didn't have a lot of flavor) to commercial lagers. However, it is noticeably different even though I don't have an educated tongue. The up side is, the few people who tried some thought it was better than commercial lager because of the extra flavor.
If you wanted to try with extract only, perhaps Briess Golden Light DME could be used (less than normal though) with very little hops (for bittering). Add sugar or corn syrup (might add tiny bit of corn flavor) to get to a O.G. of around 1.040. Ferment with US-05 (as described above) or other clean ale yeast and add maltodextrin for some mouthfeel. I haven't the foggiest notion of how much maltodextrin. Maybe 5 % of Extract weight would be a good start. Perhaps someone who has used it can chime in. You might try with no maltodextrin since the Briess Golden Light DME has 1% Carapils (for mouthfeel).
Per 1 Gallon of Final Wort:
Briess Golden Light DME 220 g (~1/2 - 1 lb bag) about 1/2 of normal amount
Sugar 180 g OR Corn Syrup 225 g (To Wort O.G.=1.040)
Total Boil 15 min.
Cascade Hops (7.1% AA) 4 g for 15 min. for IBU 9-10
F.G.~1.006 would be ~ 4.5 % ABV
SRM ~ 3
About 135 calories/12 oz. (not quite as low as light beer) mostly from alcohol.
You can cut the sugar/corn syrup down to get lower ABV and therefore somewhat lower calories.
Can't say for sure this will do what you want but I did base it off of the partial mash I spoke of earlier in this post. However, I expect it would have less flavor than that. Good carbonation will be important for this beer or it will be really lack-luster.
Hope this helps.