Can I get the internet on my laptop WITHOUT cable, phone or a cell phone?

I am COMPUTER ILLITERATE. I have a Dell Latitude D810. Is it possible for me to buy a card or something of some sort to put into the laptop to have internet access or will I have to get cable, a land line or a cell phone? I have a Straight Talk Samsung R451 cell phone with unlimited data access on it and someone mentioned tethering but I am clueless. Any answers would be appreciated. Thanks in advance! (Please keep in mind that I am electronically challenged so to speak so if you could explain things like you're answering a 10 year old I would really appreciate that! LOL)