The game gives you instructions on how it works at the start. You need to make sure Contextual is enabled in Options, then to input your answer you right click on your Notecard and enter it next to the [ANSWER] tag in the notecard's description box. When you're done, you click out of the contextual menu and hit the Enter button in the bottom right of the notecard to continue.

You should make a comprehsive guild on how to play. I don't understand how to write and subbmit answers in this game. I only ask because me and my friends want to play a game like Quiplash from the Jackbox party game