A bit hard to help you with this little information. In your microflow you can retrieve the orders based on a XPath. I assume you have a date that you want to use to filter the orders. For that you can use the > (greater) or < (smaller) operations to filter dates. See also the documentation here: https://docs.mendix.com/refguide/xpath/
Otherwise edit your question and give some more info on the errors you are getting or where you got stuck.