Welcome to Chandoo.org forums.
Based on your sample file in cell E3 of sheet 4 write following formula.
=INDEX(Sheet3!$S$2:$S$41,MATCH(Sheet4!A3,Sheet3!$C$2:$C$41,0)+1)
and copy down until you get error. Or alternatively you can choose to hide error like:
=IFERROR(INDEX(Sheet3!$S$2:$S$41,MATCH(Sheet4!A3,Sheet3!$C$2:$C$41,0)+1),"")
Please note that your current data is up to Week 20 so the formula is written upto row 41 (red marked part in the formula) where your totals will come. Make sure you adjust it when your data increases.
Once you understand this standard Index / Match construct then it will be easier for you to implement the same for the rest of the columns.