Follow this: https://github.com/Heat-Ledger-Ltd/heatledger

Download hetledger.x.x.x.zip from here https://github.com/Heat-Ledger-Ltd/heatledger/releases

unzip the file

edit heat-default.properties in the conf folder. There is a line saying "heat.api_key=". Add an api key!
go to the bin folder and start heatledger
open terminal and type in:
curl -k -s http://localhost:7733/api/v1/mining/start/this%20is%20your%20secret%20phrase\?api_key=defined_in_heat-default.properties
If you don't have curl, download it!
You need to do this with YOUR apikey and YOUR passphrase! The %20 means space and has to be included
Now you are mining

I know, the heatheads were unable to put something like this on the website. Or on their forum. Or on the github... It is a classic heathead action again!