Before Attempting this you should be able to do the following:
Parallel Handle Support
Parallel Handle L-Sit
Place your hands on the parallets with your legs in a wide straddle. Then push into a support and bring your legs up while trying to keep knees straight. If you are able to pull your feet up higher than the parallets then you may be ready for the Floor Straddle L-Sit.
The Floor Straddle L-Sit is performed in roughly the same fashion as but requires a bit more wrist strength and flexibility. Sit on the floor in a straddle place your palms down between your legs and lean forward as you press into the ground. You must pull your feet up hard with your hip flexors. If you are unable to get your feet off the ground you may elevate yourself slightly using a large bumper-plate or other suitable tool.