The selling that you've raised (上げ) is the amount sold or number of sales. Think of a graph going upward, where it's rising as you sell more things.

The reading for 売 is the one you learned with 売る. The reading for 上げ is the same as the reading for 上げる, a word you learned previously. If you know those two separate things, you should be able to combine them into one awesome vocab thing.