Apply this to B1:F1, I'm assuming A1 would never be green right?

=B1>=max($A$11:B1)

Change it to this if you don't want it to be green when the cell ties for being the highest =B1>max($A$11:B1)

The dollar signs around $A$11 is in a way locking down the start of the range, while the B1 will change with the cell its applied to