Here you can find some basics to publish a new customized theme on this group. This group is not intended to teach on how to design your own customized theme. It is to give to the theme designer a way to share Ready to Use customized themes with other users! Find more info here.
So, to make it happen very smoothly, please follow these steps:
1) To post a new theme you should post it on photos (Click 
HERE to post a new theme.)
2) Upload all pictures used on your theme on that album;
3) Upload also a picture to show how the theme would look like. Set this picture as the album cover. For info on how to get a screenshot refer to this post: How to get a Screenshot of your Customized Theme;
4) The album description should contain:
a. A brief theme description, if you wish.
b. Reference to which theme the customized theme is based on and the owner info for the original theme;
c. Customized theme developer info;
d. Version (in case of some bug fix being released);
e. Clear instructions to the user on how to install the theme, including at least the following:
i. How to select the base theme used on the customized theme;
ii. How to install the custom CSS provided with the customized theme.
f. The Customized CSS code.
5) Please, always when possible, the pictures URLs on the CSS code should be linked to the images uploaded to the post.
6) Don’t forget to apply TAGs to the themes. (updated 04-11-07) To learn how to tag properly your theme, check this post: Theme Designers: How to Tag your themes. Remember also to add the word "THEME" to your theme's title.
7) You may provide any other additional information.
The themes you are publishing here are to be used to other users. In that way:
1) The posted theme should be free to share, copy or modify by any other user.
2) Do not change/remove the basic navigation links of the theme, like the Multiply logo on the top of the page, the main (top “explore”, “post”, “invite” and “search”) menu pictures, the user headshot size, etc. It will help non-experienced users to maintain their links where they are used to find them.
3) Test your theme, if possible, in multiple Browsers before you post it here. Your theme may look different from one browser to the other.
4) IMPORTANT: ALWAYS save your theme as DRAFT before publishing it. Only when you are sure it is ready, post it to the group members.
If you want to see how a posted theme would look, see this post: Baby Girl Theme
For further information, please read this post: Group Rules
For users looking for help on how to install a theme, see this post: Basic Help on How to install the Customized Themes 
