Hi,
 
I've added a reference to the chosen file, which can then be plugged into Open().  Let us know if this works (the Open settings may need to be adjusted for your file):
sheetList = Get Excel Worksheets(file=Pick File("Select xlsx file","$DOCUMENTS",{"Excel File|xlsx", "All Files|*"},1,0,""));
Show( sheetList );
lastSheet = sheetList[N Items( sheetList )];
Open(
	file,
	Worksheets( lastSheet ),
	Use for all sheets( 1 ),
	Concatenate Worksheets( 0 ),
	Create Concatenation Column( 0 ),
	Worksheet Settings(
		1,
		Has Column Headers( 1 ),
		Number of Rows in Headers( 1 ),
		Headers Start on Row( 1 ),
		Data Starts on Row( 2 ),
		Data Starts on Column( 1 ),
		Data Ends on Row( 0 ),
		Data Ends on Column( 0 ),
		Replicated Spanned Rows( 1 ),
		Replicated Spanned Headers( 0 ),
		Suppress Hidden Rows( 1 ),
		Suppress Hidden Columns( 1 ),
		Suppress Empty Columns( 1 ),
		Treat as Hierarchy( 0 ),
		Multiple Series Stack( 0 ),
		Import Cell Colors( 0 ),
		Limit Column Detect( 0 ),
		Column Separator String( "-" )
	)
);