Use a ruler to measure the height of your decorative ceramic bowl from the outside. Subtract this number from the 12-inch measurement of your planter, the total will be referred to as the difference.
Fill the planter with small polished rocks to the height of the difference you came up with from step 1.
Set the decorative bowl on top of the polished rocks in the center of the planter and fill in the surrounding areas of the bowl with more polished rocks.
Pour sand over the rocks, stop when you notice sand accumulating on the top and give the planter a gentle shake so the sand makes its way down to the bottom of the planter. The sand will fill in the gaps between the rocks to hold the decorative bowl in place. Continue to fill with sand until it has reached just below the top layer of polished rocks. The polished rocks add nice decoration, so don't cover the visible top layer. The sand will also add weight to the fire bowl making it more difficult for it to be accidentally tipped over.
Add the Gel Fuel to your fire-bowl. Thoroughly mix the gel fuel in the canister by shaking it. Remove the label of the Gel fuel canister, then remove the lid. Place the gel fuel canister in the center of the fire bowl and light it with a long barbecue lighter.