Five solutions:
Create an extra large left margin thus forcing Word to only use the right
side of the page
Set up the page as 2 columns and insert a column break to force into the
second column
Create a 2-column, single-row table and use the 'Fit to Window' and
'Distribute Columns Evenly' options
Change the paragraph settings so that you have a large Left Indent
Use a left aligned tab at the start of each line with sufficient setting to
force the text across the page (note that if you want your lines of text
centred, use a Centre-aligned tab instead).
I expect some of my colleagues will be able to add a few more methods to do
this too.