To change the way LaTeX displays internals, use the command:
\renewcommand
This command is used in the preamble to change the way the regular command, or the command being renewed, will function throughout the document.
The syntax for this command is:
\renewcommand{name_of_command_to_be_changed}{new_command}
For example, if you wanted to change the way sections (like the introduction and the conclusion) are displayed to be the same the way that chapters are displayed, you would use the command like this:
\renewcommand {\thesection} {\thechapter.\@arabic\c@section}
The command above renews the section command to print sections in the Chapter format, followed by a period, followed by the Arabic value of the counter called section. The \c@ notation is LaTeX's way of referring to counters, which is why it is included in the command here in order to change the counter for the sections as well as changing their format.
Similarly, you could use the renew command to make sections appear differently without incorporating them into the chpater structure by using the command:
\renewcommand{\thesection}{\arabic{section}}
This would make the section command call Arabic numerals and have the sections separate from the chapters. Please see the other LaTeX pages, and the page on the preamble for more on the renew command.