Sometimes when you go to click on the images to edit them, it looks like nothing is happening but there are normally two reasons for this: -
1. The image server is already open, but it is hidden behind some of your other browser windows. If you start to minimise any open windows you have on your computer, then you should find it there behind them all.
2. Your browser is set to block pop ups, the image dialogue box is what's called a "pop up window" which means it opens up as a separate window. Some browsers have pop ups blocked by default but to temporarily allow pop ups, simply hold down the CTRL button on your keyboard and then left click on the image - alternatively, select to allow pop ups for your browser