Invoicing Functions

Hi,
I'm running Excel for Mac 2008 and am in the process of creating a workbook for my business. I have about 10 clients I sell wholesale to on a daily basis and I would like to detail the breakdown of what they get from me (I sell bagels, so people will often order 2 dozen plain, sesame etcetera) and then would like to total their orders at the end of the week for a weekly billing, that I could easily translate into Quickbooks.
So, I'd like an itemized breakdown for the total orders per day, which I will also use to summarize into an invoice for each customer per week. The database format is one column for each sale, the rows total the type of product.
I haven't yet worked with Macros but if that's what I need i'm open to it, I'll just need the basic info to get that started.
I've attached my workbook in progress, it's messy but I think it's fairly easy to see what i'm trying to do, nothing too complex. Any help you can offer me is greatly appreciated. Needless to say I've been on the web for hours trying to search for this function. I've gone through various date and time functions but can't find anything that will compound data for different dates. I've thought about saving a different sheet for each day and then just manually adding them up, but that beats the point of excel doesn't it? Thanks!!!

Sure sorry about the lack of clarity. So: This is a daily invoice, I want to be able to add the orders every day and have it add up to a weekly invoice that i then enter into quickbooks. Otherwise I have to have 7 of these per week. So I need a column sum function that will let me add (for example) 2+2+2etcetera on monday and then 1+2+1on tuesday and then something else on wed, etcetera. Otherwise i will have to have 7 separate invoices per week, and then add all of those up, which is essentially what i'm doing by hand.