1.
To add a non numbered section you just use
\section*{Acknowledgement}
If you want to insert this section on the table of contents, use
\addcontentsline{toc}{section}{Acknowledgement}
after the first command.
2. 自定义环境
\documentclass{report}
\usepackage{lipsum}% just to automatically generate text
\makeatletter
\newcommand\ackname{Acknowledgements}
\if@titlepage
\newenvironment{acknowledgements}{%
\titlepage
\null\vfil
\@beginparpenalty\@lowpenalty
\begin{center}%
\bfseries \ackname
\@endparpenalty\@M
\end{center}}%
{\par\vfil\null\endtitlepage}
\else
\newenvironment{acknowledgements}{%
\if@twocolumn
\section*{\abstractname}%
\else
\small
\begin{center}%
{\bfseries \ackname\vspace{-.5em}\vspace{\z@}}%
\end{center}%
\quotation
\fi}
{\if@twocolumn\else\endquotation\fi}
\fi
\makeatother
\begin{document}
\begin{abstract}
\lipsum[1]
\end{abstract}
\begin{acknowledgements}
\lipsum[1]
\end{acknowledgements}
\end{document}