how can I connect my phone to the computer

PS: Sorry ... you were not wanting to sync. but to update iPhone... right ?

Try this article instead:

Update your iPhone, iPad, or iPod touch

Scroll to: "Update your device using your computer"

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

All the best :)

Hi kenia231,

Welcome to the Apple Community

Apple Support have an article online that may help.

Sync iPhone with your computer

https://support.apple.com/en-au/guide/iphone/iph875319a3a/ios

Cheers :)