Here is a link to the Step by Step Instructions by the ITF: http://www.itftennis.com/media/264187/264187.pdf You have to have a current IPIN to enter which costs US$ 25.
Note that once you enter you still have to PAY your US$ 150 entry fee.
To pay your entry fee go here: http://www.itftennis.com/seniors/registration/championship-payment.aspx
Note that you have to have to get an IPIN to start the process. If you cannot remember your IPIN or password, email firstname.lastname@example.org. If your email address has changed you may have to call the ITF to get your IPIN and password. If a photo ID is required, just take a snapshot of your driver’s license or passport to send to the ITF.
The fact sheet for the individuals can be found here: http://www.itftennis.com/media/262799/262799.pdf
ENTRY DEADLINE IS SEPTEMBER 13TH AT 2PM LONDON TIME WHICH IS 9AM EASTERN AND 6AM PACIFIC TIME.
GETTING AN IPIN CAN TAKE A DAY OR TWO SO DON’T DELAY!
Doubles matching deadline is October 10, 2017 (so if you sign up for doubles without a partner, you have till then to find one amongst players who have entered).
Dates of Competition: Oct. 14-21, 2017 (qualifying rounds may take place earlier).