Adding a border on each page

Here is a possible solution based on the packages eso-pic and calc.

documentclass{article}

usepackage{calc}
usepackage{eso-pic}

newlength{PageFrameTopMargin}
newlength{PageFrameBottomMargin}
newlength{PageFrameLeftMargin}
newlength{PageFrameRightMargin}

setlength{PageFrameTopMargin}{1cm}
setlength{PageFrameBottomMargin}{1cm}
setlength{PageFrameLeftMargin}{1cm}
setlength{PageFrameRightMargin}{1cm}

makeatletter

newlength{Page@FrameHeight}
newlength{Page@FrameWidth}

AddToShipoutPicture{
  thinlines
  setlength{Page@FrameHeight}{paperheight-PageFrameTopMargin-PageFrameBottomMargin}
  setlength{Page@FrameWidth}{paperwidth-PageFrameLeftMargin-PageFrameRightMargin}
  put(strip@ptPageFrameLeftMargin,strip@ptPageFrameTopMargin){
    framebox(strip@ptPage@FrameWidth, strip@ptPage@FrameHeight){}}}

makeatother

begin{document}

section{Test}

end{document}

It produces the following result.

You can change the values for PageFrameTopMargin, PageFrameBottomMargin, PageFrameLeftMargin and PageFrameRightMargin in the preamble as needed.