Need help with rank function

Hi

I need help with using the rank function.

I found this function very complicated to use...  I can not figure out the syntax

Here is my table. all off the fields are Dimention type...

I tried to build a new Dimention like the yellow one at the picture

It should be like these:

1. On every ID_NUM the ranking is rest

2. Sorting for each ID_NUM is first by Joining date and second by update date

Eventually I want to use this new Rank dimension as a filter or for calculations.

foe example  I want to be able to filter the table on  "1" values...

I want to be able to do - count([barcode]) where ([rank] >1)

I think Its shold be as a calculation contexts Dimention...