This is the same as using the "Push To Talk" button, except you are using a key on the keyboard, instead of a button in the Paltalk room. To use this procedure, you will have to make an initial setup change from the PROGRAM window. But once it is done, you will never have to mess with it again. The key you will use is the CONTROL key, which is the key at the bottom left hand of the keyboard. 

Below are 4 graphics that show how to make the adjustment.  

Once you have changed the setting so you can use the CONTROL key to activate the Mic, all you have to do is press that key and HOLD IT DOWN with your finger to talk. As long as you keep the CONTROL key pressed down you will be broadcasting. When you release the key, you will end the broadcast and release the Mic for the next person.