Grammar; Eating with chopsticks

When you want to say "Eating with Chopsticks" I learned that you say はし で 食べる .

But why exactly do we use で?

I've only studied Japanese for two months, so would be greatfull if I could get some help with this dilemma.
Thanks

When you talking about the means/tool for doing something, you use "de", just like you would say "densha de gakkou in ikimasu" (I take the train to school/I go to school by/using the train), or "basu de kaisha ni ikimasu." ((I take the bus to the company /using the bus, I go to the company).

"De" is used in different meanings, one of them is this "using (something) to do something," and "doing something in a (location), which I am sure you have learned already or will learn soon.