It would be best if you read. https://gorilla.bi/power-query/list-generate-api-calls/ But generally, create a query like this in PowerQuery and give the query call a name. It takes on a purpose. To handle the contents that are returned, modify the code as necessary. Here, I'll suppose that I return a table.
(item) as table =>
let Source = Web.Page(Web.Contents("https://my.cmdb.server/RESTService.pl?method=lst_asset:arg01="&Text.From(item))),
Data = Source{0}[Data]
in Data
Add a column, a custom column, with:
=call([ID])
In the other table. I hope this helps you.