It’s not possible to define a cohort based on a person_id. If you want to build a cohort table with pre-defiend person_id and start/end dates, just create a .csv file and upload it to your own cohort table.
If you’re just doing your own study (I assume you are since you have the PLP question here, just make up your own cohort table (in your case: my_cohort) and make up your own cohort_definition_ids (you will just need to remember which id means ‘target population’ and which cohort_id is the ‘outcome’ you are trying to predict.
The simplest way to run the anlaysis is to execute it in R, so I would review the PLP documentation where you can find examples on how to execute analyses.