I'm wondering how do you add a news thing-amajig [Usually some how having the skin on it.] on an invisionfree forum. Sorry I can't be more specific...

& how do you make home-made skin altogether?

I can't help you on making skins. Well, I know how to change basic colors, but I definitely can't make good skins. Ask Kronakitty. 8D But getting a skin is easy...
Go make an account Here, and you'll have access to thousands of skins, and instructions about where to put what piece of coding in the Admin CP. (All have a large CSS portion, and some also have Header and Body or Footer pieces of coding. Remember to delete anything from a previous skin when you are adding a new one. The default invisionfree skin doesn't have any Header and Body that you have to delete, I think. It just has CSS)
Sorry if that wasn't clear. Have any questions?

Oh thnx, but I already knew that. Do you know if they take requests?

I think they do... Yes, they do. It's in a forum called... Skin Ticket System...

I'm not exactly sure on how to make skins, but I do know they must be hi-quality transparent GIFs. And with lots of CSS and HTML, maybe some Javascript, it can be made to display the names of forums and navagational information as well. But if I were you, I'd follow IceMaster's link(IF Skin Zone, correct?), and find a skin you like there. Also, keep in mind: Skin changers do require HTML, some even require Javascript for correct operation.
Well anyway, try that, you can definately find a good skin. *coughacidtechcough*

I've never made a skin before, but I don't believe they have to be GIFs. This skin has JPG images, and my own, when I still had forums, used PNGs.

Also, somewhere they have a kind of "make your own basic skin" or something. You submit colors for the background, for the links and text, etc, and it spits out the coding for a simple layout. I haven't used it, but I know someone who has. Try Googling it or something if you were interested...

If Agent Myst were still active he could definitely help you. He made the skin on my old forums. Of course, I bet Kronakitty will be able to help when she replies.

To make a skin you'd obviously have to make the banner, change the background colors and such in the CSS, and make the custom reply buttons and such. All this is done under the Skinning & Styles section in the Admin CP, but I'm sure you already know that. XD;

If you're starting out it's good to use a free skin and then edit it to suit your needs, such as altering the banner and icons to give it a more Pokemon look...

There are a great many Invisionfree skin builders, and they're relatively easy to make if you're willing to put a little time in it. The best skins (such as this one) have stylised images and borders and backgrounds, but it's fine if you just use solid colors for it.

Here is a decent skin generator that I used to make the skin for my forums (which looks hideous, but then again, I didn't know what I was doing. You should be fine.)