Remember that not all cars support Wireless CarPlay. Newer Kia Picanto supports Wireless Carplay. If your Picanto does not support Wireless CarPlay, you must connect with your USB cable.
If your iPhone does not connect to CarPlay in your Kia, try to set up the connection again. On your car's display, go into Settings and select Connections - find your iPhone in the list and choose to delete it.
On your iPhone, go to Settings → Bluetooth, find Kia Motors or whatever it's called on your iPhone and delete it from there too. Now you can set up your iPhone with CarPlay again. On your steering wheel, press and hold the Speak Icon button, on your iPhone go to Settings → Bluetooth, you should see Kia Motors, tap and select Yes to use the connection with CarPlay.
Remember that your car must be parked and with the handbrake on while you set it up.