Dynamic workbook reference, using Indirect on difference sheet, refering another file~

Hi All,
Please refer to the attachment.
I have a excel file called summary.xlsx, with 2 sheets.
One sheet is called summary, another is called Helper.
In the helper sheet, I will have a table with some other excel files, column which I am referring to.
In the summary sheet I will refer to the helper sheet to gather information from all other files~

How should I write the formula in summary!summary B column in order to get the information?
For the sumif condition it wont be repeated~ and I will just type "Steven" in between.
So I just want to know how can I Write the formula for the first part and the last part in the sumif formula

Thanks in advance.