one thing you could do is to create a table with only 1 cell, then you could make it to fit the page and set the border to whatever thickness/pattern you wanted.
look for the tables tab, (i think its in the tools menu) and set number of cells to 1 and number of columns to 1, resize to suit and then right click/properties/borders and shading, select the border line/pattern and that should be it.
easy for a simple document but more in depth for multiple tables etc. trial and error is key.
to set the margins, you need to goto file/page setup and change the margin sizes, bottom one needs to be a minimum of 1.4cm but the rest can be any size you want.