Need Help adding Historical Data from Excel into Power BI tables

Hello,

I have a report in Power BI that is automatically updating data daily and I'm taking snapshots once a week for historical purposes going forward.  I need to upload 12 months of historical data from Excel based on monthly extraction dates to build a trended sales report visualization chart...

The daily data is contained in two tables currently - Historical Forecast Appended and Historical Opportunities Appended...both of which I am taking weekly snapshots in an Access database to generate weekly extraction dates for reporting purposes.

The Excel historical data is contained in one single table, but the columns in that Excel table are split up into the Historical Forecast Appended and Historical Opportunities Appended tables.  

What is the best method for manually adding the necessary historical data into the existing tables in Power BI? 

Example of chart from Excel pivot table trying to recreate in Power BI:

Thanks in advance!