Is it wrong to use someone elses code?

I'm a web developer, but I know nothing about Javascript yet, and it's important on website's functionality. I think we're gonna be learning it at school, so I'm not using my freetime for it yet. The internet is full of free-to-use tutorials and ready examples. I'm currently making a website for a small company, my style is to make it 100% hand-coded (just Notepad++), but I need a image slideshow with javascript, and I found a perfect free-to-use example. Is it wrong if I use it on the website?