SQL & Graphical Query

SUGGESTED

I have the following Graphical query, the two tables are BPCUST AND SINVOICE. 

How can I set a criteria for it to pull invoices that have a date of 5/01/2018 to 5/30/2018.

When I search for this its outputting all the invoices and duplicating lines as the invoices might muliple lines. How can I search for a certain month and take away the duplicated lines.Also, under net price+tax its showing product name instead of the price. Also, what would be the SQL code.