Personally, I started on Macromedia (now Adobe) Dreamweaver, producing some okay websites, which was great at the time, but never really taught me anything, so when I started to design websites using Adobe Photoshop, CSS and XHTML, it was like going backwards in time, so I would suggest that you start straight away with using a program like Notepad++ (an extension of Notepad that has many features, such as format recognition and tabs, which is particularly useful when editing a CSS document and XHTML document).
What I'd do initially is get use to combining CSS with XHTML to position different divs on the website (a div is a container, which can have absolutely anything in it, it can scroll and expand depending on how you program it). Once you start doing this, you'll realise how simple and straightforward it really is, you'll remember all of the different codes, what is necessary for a website to be valid in all browsers, what not to do etc...
Your best bet, as Nathan quite rightly said, is to use the w3schools website, as they pretty much set the standards for XHTML and CSS, then to check that you're doing everything right during the whole process, just get used to constantly checking XHTML is valid
here and CSS is valid
here. That way you can get used to always producing a valid page, which will be very useful in the long run.
My major piece of advice is to not over-complicate anything, it really is straightforward, just take your time and read absolutely everything to help you, and don't try and learn too much at once. This is why you can't go wrong with learning CSS and XHTML, they go hand in hand and are incredibly easy to use together.
If you ever need any help then I'm here, just PM me and we'll have a proper chat about it, it'll be a lot easier for you to learn that way, it's the way that I learnt and I've got a web design business now.