How can I divide a A4 size page into 4 equal parts ?

How can I divide a A4 size page into 4 equal parts, so that I can write individually on each part. that is 4 separated column : 2 columns on upper half of the page and 2 columns on lower half of the page. I only know how to create 2 column on a page but do not know how to create "2 rows', thank you