To change the spacing of lines within the same paragraph - click "Format",
"Paragraph", change the "Line Spacing" from "Single" to something else that
suits your needs.
To change the spacing between paragraphs - click "Format", "Paragraph",
change the "Space Before" and Space after" to suit your needs. For example
if you are using a Times New Roman - 12 pt font and want double spacing
between paragraphs, either have 12 pt before and 0 pt after, 6 pt before and
6 pt after, or 0 pt before and 12 pt after.