The person you want to support should have Yuuguu installed and running. To launch Yuuguu double click on the Yuuguu icon on the desktop.
They then need to click on your name in their contacts list. It will expand to show more options. They then need to click on 'Show'. You will need to 'Accept' their screen sharing request to see their screen.
To control their keyboard and mouse - on your screen viewer you need to click on 'Request Control'. The person you are supporting needs to 'Accept' to allow you to share control of their keyboard and mouse. When they have accepted this button will change to say 'Return Control'. When you are finished you can 'Return Control' to them.