but i still cant define it in this screen

i added it in here

is there someone that could give me the steps from the beginning on how to define my tail stock so i can see it while i am programming? i have been running lathe for years now and have never had to use it but i have a job where i need to see it while i am programming and i cant for the life of me find anywhere that tells me how to set it up in the machine or control definition. Thanks in advance