Did you have volume turned up? there's a vocal tutorial that plays when starting the level. When you press start, you can press E to swtich between the cameras you placed. You can use the arrow keys to rotate the camera you are you using and you can press G to select guard move mode. In guard move mode you can scroll through the guards you've placed using the mouse wheel (the selected guard can be seen at the top text area) and then you click on the screen to move the guard to the selected desired location.
it's possible that a save game already exists within the uploaded game package as well (which means the tutorial dialogue won't play when starting the level). To delete the saved game you can open the game folder (titled Windows) click the GMTK_2023 folder, open the folder titled "Saved" and then open the "SavedGames" folder to find where the save file is. Delete the file titled "Save1" and the tutorial dialogue should play on startup.