How does a blood clot in you right leg turn into a pulmonary embolsim? any help would be great thanks

The thrombus (blood clot in a blood vessel) can break off and become an embolus (a free-floating clot) that can travel into the lungs.

I searched Google under the key words "'blood clot' lung" to get these possible sources:

http://www.nhlbi.nih.gov/health/dci/Diseases/pe/pe_what.html
http://www.healthscout.com/ency/68/497/main.html
http://www.emedicinehealth.com/blood_clot_in_the_legs/article_em.htm

In the future, you can find the information you desire more quickly, if you use appropriate key words to do your own search.

I hope this helps. Thanks for asking.