I have downloaded this app onto my iPad and not sure what it's all about! Lol

I'm under the impression this means anything on my main laptop I can look up on my iPad? If so, does this mean I have to download it onto my laptop too?

http://en.wikipedia.org/wiki/Dropbox_%28service%29

https://www.dropbox.com/

Cloud storage / sync.

No use without the desktop client on your laptop.

Install that, and then things you place in the Dropbox folder (e.g. C:\Dropbox) will be available on the iPad via the Dropbox app.

You're not actually "looking up" the laptop's content though: Items on the laptop are synchronised to the Dropbox cloud storage.

I also use it for photos now, anything I take on my SG2 immediately gets downloaded onto my laptop or tablet, also share files (legal ones!) between my friends

Dropbox is a great service,

There are also a number of other simler services out there,
Including,
https://www.sugarsync.com/
and
https://drive.google.com/start#home
There are more, but these are the ones I use.