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 my Icom 745, you’ll need an interface box to connect the audio to/from the radio to the computer, and the PTT from the computer to the radio. These can be built, or DX Engineering has a number of 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