Using the "AND" and "OR" operators

Using the "AND" and "OR" operators

I know this is an easy question for the experienced, but I am not.  I am a network engineer pulled into a project for a client. I have created a form for inquiries, but am having problems creating some of the required views.  I need a view that will filter records based on the following three criteria.

If the attorney_week matches one of my values AND has been added within the last 8 days.  But I also want to display any records that have an empty/null value for the final_disposition field regardless of when the record was added.  This script below was created using the GUI, but I have read on using the "OR" command and no matter what I try I cannot get it to work.  I am willing to pay to get this completed.

((Attorney_Week == "TMM" && Added_Time >= (zoho.currentdate  -  '1W:1D:0H:0M:0S')) && Added_Time < zoho.currentdate)


TIA 

Bill Hankins