There is no way to get a someone on Spirit to communicate with you if they do not choose to do so. Having said that, to connect with someone you knew when they we in physical form simply hold their image in you mind and think of them. This touches the vibration of that incarnation. If they want to connect with you, they will come into your vibration. It helps to have a well trained medium (or be one yourself) to facilitate communication when they arrive.
~Message from Gene