Sharing screens is really easy and can be a great teaching tool.
Start by opening skype and signing in with your username and password.
Here is what the skype opening screen should look like:
From here, you will want to chose the student/person that you would like to share screens with. In this case, we are choosing Mona Lisa.
This will bring you to the contact page, it should like the screen shot below.
Click on the second round button in the top right of the screen. You will see a drop down of choices, select "Share Screen...".
Once you choose the share screen option an overlaying window will show. Choose the screen you'd like to share and press start. Your screen sharing session will now begin!