The page details the JT65-HF mode of operation, and lists resources available to the community about this mode.
Article on eHam.net
eHam.net has an article on the JT65-HF protocol.
What radio will you be using?
If you’re using a radio like a Flex, or an Icom 7300, they have an audio interface built into the radio and you simply connect with a USB cable.
You Need a Radio Interface?
An older radio, like an Icom 745, will need an interface box to connect the audio and the PTT to the computer. You can build an interface, or DX Engineering has some interfaces at https://www.dxengineering.com/search/part-type/digital-mode-interfaces
There are a number of software programs available, once you’ve got the hardware set up properly. WSJT-X is the original, created by K1JT, Joe Taylor. That page is available at http://physics.princeton.edu/pulsar/K1JT/wsjtx.html
RTTY is available with the MMSSTV software at https://hamsoft.ca/pages/mmsstv.php