How to customize a specific content type display? I have a content type which has many fields. My problem is that all fields displays in rows like this picture:

How can I customize these fields? for example I want them to arrange like this one:

Also I want to change some font-size (in the red box in second pic). What should I do?
thx.
with the FieldUI, (enable in modules), you can place the fields,
see here /admin/structure/types.
with display suite you can even do it more sophisticated.

but in the end you want to have your own theme, or adjust the one your using for css etc.