Web Developers Help

Hey I have constructed my first website for my friend but I needed some help regarding the php and mysql stuff.
I am very familiar with Html Css and Javascript, but my friend asked me to have a 9gag like ability to upload images/videos with some text underneath.

Do I need to have the Domain Name and DNS for that? (before i can actually start coding it?)
And not really sure the "real" differences between the Domain Name and DNS.

Also I like to keep things simple so the whole thing is designed in normal notepad I know i need to download php which is a bit of a pain but oh well..
Anyone with some info,, would greatly appreciate it Thanks.

You're in over your head, no offense.