How should one create the phenotype file for a three way admixture population

[99aarreola]

Hello, I am following along to the tutorial before I do my own dataset. I finished the tutorial, and saw it says in the future to create your own phenotype file. Would it be possible to have more written information on ways to find this information in my own dataset and create a new file that reflects the columns? I will be doing three populations. To break it down: 1) how do find my IDS, 2) corresponding Phenotype column, 3) Covariate column, 4) and create a text file that reflects this information (can I use excel and save as text?)

Thank you