How do i level my toilet and what do i use?

Toilet pans should be screwed down so either the screws have gone rotten or don't exist.
If tiles are lino type on wood floor it's comparitively easy in that you can drill into the floor through the screw holes in the pan but be carefull measure the hole size and get a auger bit to fit. Drill into the floor but NOT right through just enough for a screw to get a purchase.Brass screws around No 10 2 1/2 inches long but measure depth use a knitting needle through the hole then add around 1/2 to 3/4".

Solid floor and solid ceramic tiles:- afraid you'll have to remove the pan. The easy way to mark the screw holes. Large piece of cardboard sit the pan on the cardboard and poke a knitting needle through the screw holes into the cardboard draw around the pan to get base shape. Cut out the shape and place it in position of the pan hold it firmly and drill the holes for No 8 or 10 screws. Sit pan back in position and measure with a knitting needle through screw holes to get rough length of screws needed.
No' 8 or 10 rawlplugs depending on size of screw
Screw length around 2 3/4 to 3 " long.
Peice of cardboard.
Flat type tap washers with hole in middle for rubber gromets under the screw heads to protect the pan base when tightening. DON'T OVER TIGHTEN OR YOU'LL CRACK THE BASE.

BOB
November 2008