Generally, you have to have a table of transactions (sales, if you prefer) that include a date and a quantity of items sold and WHAT was sold. This might in fact be a parent-child table involving a sales invoice that probably includes the date of sale and a line-item table that lists the quantity sold of each item individually.
Once you have that, you can create a JOIN query of Invoices to LineItems showing all line items grouped by invoice number or by date or by item code. Once you have a grouping (look up GROUP BY for details), you can do what is called an SQL Aggregate such as SUM() or COUNT(). To get total sales you would probably use the SUM() aggregate. To limit the date range, you put your date restrictions in a WHERE clause. There are only about a gazillion ways to do that so you would need to tell us more about your setup.