Originally Posted by Ironfish653

I'm gonna try to be nice, because it's apparent how much you don't know what you don't know yet, but there's more than just changing the shifter to get "more speeds"
On the surface, bikes are simple, and they work and go together the same way, but, as they say, the devil is in the details. Bikes have gone through a lot of specialization in the last 15 years or so, especially when it comes to the drivetrain, and you can't just mix and match like you could 30 years ago.
A bargain price, "Big Box Store" bike like your Kent is built with the most basic components (that will still function) but they are barely compatible with the things you'd find on even a mid-line TREK, for example. In order to get the 10 speeds you want, you're going to need the shifter, a 10-sp compatible derailleur, a 10-sp cassette, and a cassette rear wheel, because the 7-sp freewheel on your bike won't support 10-sp. Ironically, the "wire" (actually the shift cable) might be the only part you could re-use..

The question is whether a bodged together "upgrade" that exceeds the original purchase price of the bike is worthwhile, or just look for another bike (maybe used) that has what you're looking for.