Don't laugh if my question sounds stupid.
My BB 8130 (Sprint) does not have the Internet Browser. I recently add a data plan for it, but still can find a way to surf the net on it.
Yeah, bring to the store, they'll set it up for me. That's easy. But can I do it myself?

Have you re-sent your service books since you had the data plan added? If not, Resend Service Book by logging in to your BIS account

How can I resend the Service book? You mean I have to log in to my Sprint account and send it from there?

Yes, login to your Sprint BIS . . .
here's a link... https://bis.na.blackberry.com/html?brand=sprint

Start with this: Battery Pull then Menu>Options>Advanced Options>Host Routing Tables>Menu>Register Now.

If that fails and you have not configured a BIS Account yet it may be easiest to just call the carrier and ask then to resend the service books.

In my experience all you need to do is menu>options> Advanced Options> Host Routing Tables> Menu> Register Now

Go back to your home screen.
Icons should appear ( browser + other icons)

If only that does not help you then powercycle the device... and repeat the steps above.