Again, try to be as specific as possible in your directions. One main goal of using a webquest is to provide students with opportunities for autonomous learning. You want them to try to complete it with very little additional help.
You can see that I even provide step-by-step instructions with pictures for how to use the software, in case they aren't already familiar with them. You don't have to do this, but it is a great idea if you have the time. Try to write it all in the target language, using pictures to give them clues!