Contact your local BSA District Executive. He/She may have already did the ground work, such as interest surveys in the high schools and colleges in the area. to Establish an Explorer Post you will need at least two adults over 21 to sign on as advisors (one of each sex) then have a committee of five and at least five Explores. Starting is not that hard - recruiting is hard though. I was involved in an aviation Post for three years. once the initial group went their own ways it was hard recruiting.
Good Luck
EMT-B 55