Help calling data for a from a specific cell in another sheet.

I can never remember if this is an index, indirect function but here goes:
Example: the comma means in a new column

Row 1: 2000,1000,2500,1300,200
Row 2: 5,4,5,6,6
Row 3:

The numbers in row 1 indicate a value in "sheet 2" that meets a criteria.
The numbers in row 2 are some constant
In row 3 beginning in column "A" I need a function that I can call on A2000 in sheet 2. Then when I drag it over it will call the number in B1000, C2500 etc...all from sheet 2.

Thanks in advance!!