You have to extract it first. You do that by clicking the file once, then the three dots on the top right of your file folder, and then pressing extract and accept. After it loads you double click the TADDS with the little lady icon next to it.
Some games don't name their little lady icon, and its instead called (something) 34, which is irrelevant to this game but needed knowledge if you want to download other games on itchi.io. Always click the little redhead lady. Though sometimes creators will put in their own custom picture for the game, but you should be able to recognize it anyway because it'll match the vibe of the game you're downloading.
Also Also, don't place the icon on your desktop. When you open it that way, it doesn't always work.
The control button lets you skip dialog btw, and escape will lead you to the save/load screen.
But if you mean how to play a visual novel/otome, just click the boxes and it'll lead you to different dialog options. You also put in the name the charecters will call you, and in Zoobles route there's a scene where you'll need to click on one of two pictures shown to proceed. For dialog you can either click or press spacebar, though in some games spacebar gets rid of the dialog box until you press it again to see the entirety of the art, but this one doesn't do that. There is, however, a gallery.