Crude oil prices: value conversion

Hi everyone,
as part of a research project, I need to conduct an analysis of crude oil prices.

The attached excel project contains Brent Europe daily spot prices from Datastream for the past twenty years. Unfortunately, I am having difficulty converting the daily values into weekly numbers.

I have tried implementing some of related advice that has been posted to this forum, but it was no help. Any help would be greatly appreciated!

Cheers,
onze