can u have an internet connection without?

[71Makaveli96]

ok, thanks he called the internet provider & they told him that in order to set it up for the first time he needs to set it up with a computer, my question now is since i have the same internet provider Yahoo DSL would it mess up in some way or another if i set it up for him, like after im done setting his up MINE should work like normal right, dont want to mess mine up