Adding pdf pages into latex

I am trying to insert a PDF file as an appendix in my latex file. But when I add the usepackage{pdfpages}, I have some compiler errors as

! LaTeX Error: Missing begin{document}.

Do you know how can I solve this problem?

documentclass{article}

usepackage{pdfpages} 

begin{document}

includepdf[pages=-]{myfile.pdf}

end{document}