Hi Bev, there's a tool called FileOptimizer which I personally love.
You simply select a folder, and it'll compress every image within that folder. It's open source, so free for everybody to use. But the drawback of this, is that it looks a bit dated -- but for your needs I'm sure it'll be just fine.
Look here: https://sourceforge.net/projects/nikkhokkho/files/FileOptimizer/
Also note: You should be scaling your images too, search Google for "GTMetrix", they have a tool which can help with scaling.