You can't do this in Ligtroom, you need to use a pixel editor, like Photoshop.
Also be aware that Lightroom is not Photoshop and does not function in the same way as Photoshop.
Ok thanks. I have an older version of photoshop elements that I can use to do this. I've recently started using lightroom but wasn't sure if there was a way to do this as well. I have a lot to learn about lightroom. Thanks.