These particular candleholders are hung using hose clamps secured at the mouth of the jar. Then I used soil and white stones to fill the jars enough that a small citronella tea light candle could be dropped in and easily lit.
Some other fun variations include using sand, just stones, or whatever sort of materials you may find in your backyard. You could even create a mock-terrarium candleholder using soil covered with a bit of moss and a candle. Also try grouping together a variety of sizes and shapes of glasses or create a more modern, streamlined look by lining up identical jars.