Melting sugar on creme brulee with blow torch
The technique for creating a proper layer of melted sugar on your creme brulee involves three important elements:


After you add the sugar, gently swirl the ramekin to create smooth layer of sugar. You don't want it too clump or be uneven.
Gently 'kiss' the sugar with the tip of the flame, moving the flame around to heat evenly, just until the sugar starts to flow.
Hold and rotate the ramekin to cause the melting sugar to flow around the cup and form an even layer. 


Your goal is to distribute the heat, and sugar, evenly and smoothly around the top of your custard.

The technique to use is easier to pick this up by seeing it rather than reading about it. Alton Brown did a segment on Creme Brulee on Good Eats where he demonstrates the technique. 

(if the link fails, you can Google "Alton Brown Creme Brulee on You Tube")