You need to visit a homebrew store for a sanitizer. The only one you'll find at a grocery store is household bleach, but I wouldn't recommend using that as it is not no-rinse.
If you can find it, StarSan is your best bet.
Some people use kegs and co2 to push clenaer and sanitizer through their lines. I built one of these for cheap: http://www.homebrewtalk.com/f51/diy-...leaner-226497/
. I'd rather have my kegs full of beer than sanitizer...
First I push out the beer from the line (if there is any) with water. Then I push through some beer line cleaner and let it soak for 20 minutes in the line. Then I rinse with water, and push starsan through, and hook up the new keg.