Hamed,

1. Start with a trainer not a sport, this will save you alot of angush.

2. Find a field

3. Find an instructor at that field.

4. Get AMA insurance.

For a trainer I like SPADS ( spadtothebone.com ), but for whatever you get be carefull these are fun, but are not toys. Take your time and learn the basics, The rest will come as your skills grow.