There was a post about the levetta under Froth & Bubbles not long ago. Koffee Kosmo posted the following instructions and people seemed to find it really easy to do and got good results quickly. Give the following ago:
Purge water from steam wand
Use a loose hand not stiff
At first use 300 ml jug and fill to just under the lower part of pour spout
Place wand just under milk in the middle of jug at 90 deg (no angle) and only give it air in the first second no more
Important - turn on steam to "full"
Allow steam to do the work when milk starts to foam keep wand 90 deg but move jug to one side until the steam wand hits the side of jug
This all happens in about 10 seconds and before you know it you have micro-foam