I need help building a workflow in Sharepoint.

When an item is added to List B3, I need the workflow to search the Audit Entries List based on two fields and then update that audit list item.

I can query the Audit Entries List based on the two required fields, but I don't know how to store that result and then get the "update item" task to choose the correct list item to update.

the "update item" task doesn't allow me to select from variables to update, it wants to match a column name from the Audit Entries List. The only non-column name options are the ID and the Workflow Instance ID but I don't know what the return values should be to use those.

Help!