Custom Week filter

Sorry if this is a simple question however, I am new to Power BI, Power Query, DAX. I do however have expereince with sql, php, excel, etc.

My company runs a custom sales week Tuesday - Monday. 

I need to be able to filter my reports on Current Week and Previous Week. 

Example Today is Tuesday 10/18. So my current sales week would be 10/18-10/24

My previous sales week would be 10/11-10/17. 

I'm assuming that it will invovle in either (A) creating a custom column in my date table and/or (B) creating a custom date range table.

Thanks for the help. Please give detailed instructions and pretend like you're talking to an English major. This is all new to me.