layouts arent necessarily my area of expertise, ive dabbled here and there with them... and i dont think we have an expert on board who just does layouts.. however i can ask you a couple of questions. what type of layout are you exactly trying to create? or what look/style?
For the coding, I suggest you use dreamweaver or Frontpage, you can upload your template there, and slice it to different pieces (wich will lead to different links). http://www.actden.com/fp2000/java/index.htm (for some help ;))
When it comes to making layouts, how to go about it can get as many different responses as there are layouts!
Like applejuize, she uses dream weaver or Front Page. I differ on my opinion on both, as I feel that if you really want to get down to the nitty gritty, the only pal you'll need to start with is a plain .txt file so that you can start at the basics and rip it apart step by step.
What follows is just my learning experience! If it's good for you, then that's awesome! If it isn't, well we all do things differently and there's no harm in that!
If I were asked what I'd recommend to a new designer, I'd recommend to familiarize yourself with lj specific tags, the S2 system (Even I'm still trying to figure that out--but since lj plans on merging s1 and s2 in the sometime future, if I want to continue learning and making layouts, I've got to get to know it), basics of HTML and css as a must.
There are several handy tools/tips I'd tell a new designer to remember too. Don't design for a specific monitor resolution if you want to hit a broader base of users for your designs. Don't design in just one browser either. (I learned this the hard way, being a once hard-core IE only user).
I use Fire Fox now, as well as IE 6 & IE 7 Beta to view anything I code to make sure they display properly on both. Now, you don't have to rush out there and get every. single. browser. In fact, you don't have to work with any other browser than what you like. For me however, I feel it's important to have at least two or three main/most popular browsers for checking a design.
Second, the reason why I went to the Fire fox side, is because of a few handy tools Fire fox gives for -free- as tools and add ons for designers. One is a tool called "Windows re sizer." I can view a design in resolutions of 640x 480, 600x800, 1024x768, 1280x1024 and if you have it, 1600x1200 so that I can see how someone else with a different resolution than mine, sees the layout.
Second, there's a handy add on that lets you edit your css from the browser itself.
Lastly, I'd just like to emphasize that what worked for me, was learning the basics, definitions and functions of HTML and css, since almost all the layouts I've ever made/come across use 80-90% of css to portray a layout's effects. (Also --the tricks you can do with css once you learn the ropes can be amazing.)
In doing so, I think you'd have layouts that can be used by a broader base of users, have layouts that display properly for a larger base of browser users, and generally just have prettiful layouts with less display issues. (Sometimes when I designed a layout in IE only, then viewed it in Fire fox, none of the css or images displayed!)
Okay...wow. Did I type enough? That's my opinion from your friendly neighborhood ninja-css-lady.