The maximum amount of cases you can load is 500 so usually people sort cases by that. In the first box you'd put your group (e.g.WAC2190138500) and in the second box 500 (or less, depends how many cases you want to load, it takes a bit).
Here's a link to a sheet where people track the case updates from USCIS for last years filers https://docs.google.com/spreadsheets/d/15hiSOTm85W1CG6c0jzQ8B7lXLo1JEwsWKr3zIszC2Zg/edit?usp=sharing