Parallels on Macbook Air not displaying on IMac via Thunderbolt

I have Parallels installed on a Macbook Air. I have connected the Macbook Air to an iMac by Thunderbolt cable. On pressing Command F2 the Macbook displays on the iMac as expected. However, when I open the Parallels desktop or any Windows applications they are displaying on the Macbook Air but not on the iMac. How can I get my Windows applications to display on my iMac please?