DNNCreative is an excelent starting point. Skinnning does though, for a novice, cause some confusion that isn't really needed. I had, and still have trouble from time to time.
Some advice from my failuers :->
1) Make sure you have a solidly installed Development environment. Google Michael Washington, he has step by step instructions on setting up your dev environment up best.
2) Forget about the source code version of DotNetNuke right now, you don't need it for anything at this time. Just use the install version on your dev env. it's quick, easy to install, and if you screw it up you don't have to wait a month....But do follow michaels instructions to the letter.
3) Post any and all questions in here!! Seriously, everyone is very friendly here....we want more poeple using this :->
For skinning specifically, the problem learning it is that most of us already know alot of HTML, and at first glance it looks super easy, so we blaze through the instructions, miss something, then spend hours hunting down what we missed.
Instead, do this, create a simple HTML doc with 1 table, put all the tokens in it and a content pane. Copy the XML file from the included skins into your folder wiht your HTML file. throw it in a zip, and upload it to your development copy of DNN and load it.
Then open Virtual Web developer, tweak the HTML, go back to IE, parse skin package, look at it, tweak some more, parse again.
Also, there is a debate on whether to skin using ascx or html with some people. I say use HTML and XML to create your skins. ascx sounds like a good way, but you end up typing alot more than needed. HTML is the way to go, and use the parser. Thats the way the smart people who actually made this program intended, I"m sure they have good reason for that :->