Plug in your Manycam first.

Then start the Tinychat application.

I'm trying to use manycam with tinychat. 

everything went fine before. But today I got a message "cant connect to video source. Please check another video capture device."

There are two options to click on tinychat: Manycam and Logitech. Manycam works well without on tinychat. What should I do?

I have installed Manycam and it Works fine.

But Manycam doesn't show up on the list of tinychat options?

TO PPrashanth: reboot your computer and check again.

Open up manycam when you choose it as tinychat cam and pick an option on manycam.