Go the FAA website and get the info from them, then select your flight school, once you have paid them go the TSA website and start doiing the application..(the TSA won`t process your application until they get notified from the flight school you have selected that you have indeed registered and paid with them) if you doiing an initial type rating plus ATP test you will have to apply for class 2 training request. Read the application carefully to see what applies to you. You will have to scan every page of your licence, medical, passport and last 3 pages of your logbook, make sure they are really large and clear or you will have to do it again. Get a US visa, then once you get to the US, you can only do the fingerprints at certain locations, some flight scools do it but make sure where you can do it. I am not sure but I think you might be able to do it at the US Embassy in Pta, but find out when you doiing your visa application. You can start your ATP groundschool or type rating ground school but you cannot do any training on sim or aircraft until you have received final approval from the TSA. I recently waited 2 weeks for a recurrency training request just because of illegible documents, and we go there regurlarly. With the new system you wont have to resubmit unless you have a change in your licence and or passport!
PM me if you need any more gen. Good luck.