Firstly, if it's very windy outside, stay home! This is a light-to-moderate wind kite and won't like being launched in a gale. There's our original 2-Skewer Sled in the photo up there, flying in a very light late-afternoon breeze. It required those tails to fly stable.
Assuming there is some breeze outside, just dangle the kite at arm's length until the wind catches it. As long as you feel the kite pulling, let out line slowly by taking loop after loop off the winder.
Another approach is to get a helper to hold the kite up and let it go, on the end of maybe 10 or 20 meters (around 50 feet) of line. This way, the kite soon gets high enough to make it easy to let more line out.
Have fun flying, and I hope you've enjoyed learning how to build a Sled kite!
Now, just in case you have actually made and flown this kite at least once already...
You've probably read a kite-flying story or 2 of mine, after they appear under the "what's new?" link on this site. I sometimes wonder if anyone else has made and flown this particular design...
If you feel your efforts really paid off when the the kite finally got airborne - please type a few paragraphs in here telling us all about it!
P.S. I can only accept stories of at least 300 words. Just mention a few details like the weather, onlookers, the kite's behavior and so on - 300 words is easy!