Please instruct me on how to find the button for updating to new version!

What model is your phone? If you have a 6 or older you won't be able to get a newer version.

• If you have an iPhone 5S or 6/6plus, the highest you can update to is 12.5.5

• If you have an iPhone 6S through 13, you can update to 15.3

Go to Settings > General > Software Update.

Update your iPhone, iPad, or iPod touch -

https://support.apple.com/en-us/HT204204

Go to Settings > General, then tap Software Update. If you see two software update options available, choose the one that you want to install. Tap Install Now. If you see Download and Install instead, tap it to download the update, enter your passcode, then tap Install Now.

You can try waiting or you can also try to update using your computer.

Update using your computer -

https://support.apple.com/guide/iphone/update-ios-iph3e504502/ios

You should have an option to do it now. If not make sure you’re on a wifi and charging at the time of when updating will take place. Also, don’t be on your phone, watching videos, or anything like that.

i added directions for you just above this comment to start the update now.