As a 60-something myself, I can tell you that it's really a lot easier than you realize. You may be overthinking things. So, let's verify a few things and get you up and running. It'll be easier than you think.
You say that Roku sent you a link. There's no context, so I'm guessing here. Are you setting up a Roku for the first time? If so, those links have an expiration. I'm not sure how long it is, but you may need to start over in the setup process (assuming that's what we're talking about).
When you get the link, it comes in your email, right? If your email client (Windows Mail, Apple Mail, Thunderbird, Outlook, whatever) is properly configured, simply clicking the link will open a browser window with the information you need.
If you're using a browser based email setup -- for example, opening a Gmail account by going to https://gmail.com -- then it most certainly will open the link when you click it.
There should be no issue with clicking the link. However, that's not a 100% guarantee. If clicking the link in the browser (the last time I got one, it was a purple button in the email) doesn't work, then hover your mouse over the button/link, and right-click > copy. Then open a browser tab and in the address bar, right-click > paste. Then press enter.
DBDukes Roku Community Streaming Expert Note: I am not a Roku employee.
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Re: How to move the link Roku sent me to my internet browser
@JKENDALL Are you setting up a new Roku device? Are you trying to setup a Roku account for the first time? If you do not have this problem solved the email that was sent has now expired. If you are setting up a new Roku and creating a Roku account open the email on your computer instead of your phone.