Depending on the model it could be
A dedicated button, located above the keyboard.
A toggle switch, located on the front or side of the laptop.
The FN and the key with the wireless icon on your keyboard.
The key combination Fn + F3 is also used.
Watch this henry. You need the id password of your router if it has never been connected. If it has previously worked just make sure you select the right one from networks available after right clicking on the wifi logo bottom left of your screen in the bottom bar. The wifi logo is probably an ascending row of vertical bars.
Another question henry. Has that laptop ever been connected to your router. It seem that you have a w10 system running on a different device. If it has never run on your router it will need installing on the w7 acer. Can you look in devices to see if your acer has the router listed there?