As with your earlier post, I think you'd be better off asking for help in your native tongue rather than English, as I'm not following you too well.

Css code can help change header picture?

Just set the image as a background of any element and then you can change it with css

¥

I have more subdomain in website need to user can use css for change head picture for blog us. You (¥åßßå) have a ex. code css for change it from back system?

There is a checkbox on each blog's "Blog Settings -> features subtab for "allow users custom CSS". If you check that box then the user has to upload to their own media/users/them/ folder the image they want as their custom header and a style.css file that will over-ride the official one.

So it would be up to you to teach your users what that file would have to look like. For example since I use the evopress skin I uploaded a style.css that looks like this:

#Header {
background: #73A0C5 url(header.jpg) no-repeat bottom center;
}
#Header, #Header a, #Header a:hover , #Header a:visited{
color: red;
}

A different skin might not have #Header, so obviously this custom file has to be written for exactly which skin you want to let people customize.

Hope it helps!

EdB thank alot you have a time for revirw my web? I have problen about tool when post. i dissatisfy when post some picture from post i use lightbox but can not to see button in tool post.

Let's not go too far off topic here in the "Templates, skins, XHTML and CSS" forum okay?

Your application of b2evolution is EXTREMELY hard to do well, but it looks like you are getting there. This software, at it's very heart, doesn't want to have automatic blogs for people is what I mean. It was designed with the idea that "The Admin" (the person who runs the installation) somehow knows all of the bloggers.

My best advice to you at this point is to slow down. ALWAYS ask yourself if the thing you are trying to do is (a) critical for the application to work or (b) something that would be nice for your bloggers to enjoy. If the answer is (b) then give up on it until such time that you are starting to find your own answers. For example I've written about using custom styles a couple of times, as have a few other people here. It's okay to ask of course, but what you are doing is so very complicated that you really need to focus on the very important parts. Not the nice parts.

i dissatisfy when post some picture from post i use lightbox but can not to see button in tool post

That you need to ask in the place where "lightbox" plugin was announced. I think it is a plugin - right?

One other thing, and please do not take offense, but your English is very hard to follow. I can normally understand a question even if the spelling or grammar is not what they taught me in grade school, but sometimes when I read your questions I think I've been drinking again 8|

My advice again is to slow down. Maybe you can get someone to help you with putting your question into English? Maybe before you hit submit ask yourself "will the English-Only people understand" will make it much easier for us to help you. I'm sure you would be much happier if we had a Thai forum, but hey if we did *you* would be answering all the questions there! :D