hopasholic the best way to think of it is as an online scrapbook. So imagine if you were doing up your house and your were flicking through a house magazine. Each time you found a picture you liked you might cut it out and stick it in your scrapbook.
So Pinterest is basically a virtual way of cutting out and sticking images you see online. So you can make lots of different folders and create your own names eg clothes, house folders (by room or accessory type eg lamps, rugs etc), by hobby, recipes etc.
When you create a Pinterest account you can install a little pin at the top of your toolbar and then if you see an image you like on a website you click on your toolbar pin, it then brings up a summary page of all the images on the page you pinned and you select the one you liked. It then opens a box with a list of all your Pinterest folders, you select which folder you want to use and it pops the picture in.
So for example when I was doing up my daughters room I was 'pinning' photos from the John Lewis website of bed linen, or the harlequin website of wallpaper etc. then it stores all your online ideas in one place.
The folders on Pinterest are called 'boards'. When you go into one of your boards and click on one of your pictures it also provides a web link to where that image first came from. So if you found a great article you need only pin one image but you would still have a link to that original article.
The other thing you can do is browse other people's boards or images. So you could search on Pinterest by a word or person eg French chic style. Then loads of images that other people have pinned will come up. If you like any you can then pin them to your own board. This is called 're-pinning'. When you click on someone else's pinned image it will tell you who pinned it and to which board. Quite often people pin one image to similar types of boards to your own, therefore browsing that persons board may lead to further inspiration.
Hope that makes sense, happy pinning!