How to create a source and destination worksheets in Excel?

I am struggling with an excel feature regarding creating a Source and Destination workbook.

My Source data comes from the web. So I download it, create few new columns and functions and use it to make a dashboard on Power BI. This dashboards needs to be updated as and when data on my source changes.

Since I have to make few changes to the Source data before making dashboards on Power BI, I cannot directly link the data for automatic updates.

The idea here is to create a Destination excel sheet with all necessary columns to connect on Power BI. And then download the Source file and create a link. In this way I should be able to download new Source File every week which will update my Destination file and finally update my dashboards!!

How can I make this happen? I am not excel expert and really need help!!

PS I am using office 365, Excel version 2102

Thanks for the suggestion. I have changed it now

As with the links, I had read them previously but it did not answer my question.

I need to make changes to my Source data before linking it to Power BI. That is adding few more columns and functions to represent certain data on my dashboards.
And since there are new rows of information every week. I am currently downloading new Source file(this is in excel format), recreating the required columns and recreating dashboards again.

So the solution I am looking for if it is possible to create a Destination file and add all these columns. Create a connection/query/VBA code that can link the downloaded Source file and update new rows in the Destination worksheet. As the Destination worksheet will be connected to Power BI, there will new information on dashboards.

This will eliminate the tasks of recreating columns and dashboards every week for me. And the only manual work will be to download Source file and refresh link.