How to do this... (these are the basics!)
It's VERY simple to do some basic stuff, and can be done right in Windows, you don't need any understanding of Linux at all.
You will need a zip utility, this can be 7zip, Winzip, or Winrar. What you do is look inside the zip, then drag and drop things into and out of it. If you rename APK's to zip, you can open them as well. Sound simple? It is! I use Winrar.
Bits of information you need.
Warning: If you extract everything and try to re-compress it, you will break things. Being Linux based, Windows will lose files making your rom not work. So only open and drag things in and out. This applies to APK files as well.
Build.prop, there isn't much here to mess with, but you will want to change the 4th line
Replace the stars with the name of your rom, this will show up in the “about phone” section.
Do NOT change ro.product.model or ro.product.manufacturer, you will have issues in the Play store if you do.
Boot animation.zip is normally stored in system/media, however I did not include one. These can be like mini movies.
The “Aeneas” animation will be covered if you use a boot animation. You can change the Aeneas animation by changing two files in system/framework/framework-res.apk The files are located in assets/images/ and are called android-logo-mask.png and android-logo-shine.png. These need to be PNG's and you cannot change their size. The mask has clear lettering, the "shine" slides across behind it in a loop. It's a simple animation, but you can do a lot if you are creative.
Default wallpaper is also stored in framework-res.apk in the folder res/drawable and is called default_wallpaper.png
Apps are stored in system/apps
Apps stored here cannot be uninstalled, they must be deleted. However, they don't take up as much room. Not every app can run from here. Uninstallable apps are in data/app. Anything put here can be easily uninstalled by the user through settings. Most apps can be run from here. Do NOT put pay apps in your rom.
If you open a statusbar zip, you will see where the files go and what they replace. Feel free to use the ones from Harmonia. I will link them in post 3.
Changing the installer.
The installer is located in META-INF/com/google/android. The actual script is called updater-script. DO NOT edit with notepad. You need to download Open Office and use Writer or download Notepad++. Using notepad can mess up the file. Really there is nothing in here you need to mess with, but you may want to personalize it. It's fairly easy to understand what you want to change as it's very simple code.
META-INF which contains the installer also has the signing, if you use the optional statusbars, you don't import this. If you do, you will wipe out the rom installer.
Changing XML files...
If you open an APK or Jar, you might not see all of the XML files or folders. There are Windows based APK tools that can do this, but a simple zip tool cannot. So if you are looking for a file and cannot find it, this is why.
Signing your rom
Signing is optional, but you will want to tell your users they will have to disable the signature check in recovery. If you still want to sign it, search Google for “sign zip”, you will find PLENTY.
Hosting your rom...
If you are starting out (obviously you are), Mediafire is a good option for the rom. For images for your thread, Imageshack works.