Loop Through Cells to Find Matching Data

For some reason I just cannot get my mind around this...
Sheet 3 has all the Data.
Sheet 1 is the Summary.
Sheet 1 Column B I have Employee ID (EID) #'s (all duplicates etc removed), In Sheet 1 Cell C1 I have the Date and now I need to do the following:
Sheet 1 Column is where I need the Data Returned
Take the EID located in Column B, Look for it in Sheet3 Column G AND Look in Sheet 3 Column A and match the date that corresponds to Sheet 1 Cell C1
I need this to loop through each cell in Sheet 1 Column B until the end.
For some reason I have ALWAYS had a problem with understanding this.

If anyone can assist and explain the steps I will be grateful!