As I read what you've told us so far, you've not yet connected your TV set to your router. There's no point trying to get any apps to work until you've done so!
Look for the 'WPS' button on your router. (Most modern routers have one). It will probably be fairly small and it will either actually be labelled 'WPS' or it will be marked with a symbol something like this:
https://d35v9wsdymy32b.cloudfront.net/v1/images/p7Vb546XbgVDMBwH5zbgZcI1.png
I'll assume that your router has such a button and that you've managed to locate it . . .
Press the 'Home/Menu' button on your TV's remote control. (It's the one with a 'house' symbol on it, in the middle and about a third of the way down).
Use the 'Up' and 'Down' buttons to get to where 'Settings' is highlighted and then press the 'OK' button.
Similarly, locate and select 'Network'.
Again similarly, locate and select 'Press WPS on your wifi router'.
Once you've selected that (by pressing 'OK'), go to your router and press its 'WPS' button. Your TV set should then connect automatically to your router.
Once your TV set is connected to your router, you can access Freeview Play by pressing the relevant button on your remote control. (It's on the left-hand side, below the 'Netflix' one.). Having done so, you can then select your chosen catch-up app, such as BBC iPlayer or ITVX (which might still be shown as ITV Hub on your screen).