By "division bar" do you mean:
a. The horizontal line that separates the numerator and denominator of a
common fraction?
b. The diagonal slash that separates the numerator and denominator of a
"shilling" fraction?
c. The division symbol (÷)?
d. The "long division" frame that's similar to a square root symbol?
If it's (a), (b), or (d), you choose a "fraction template" from the
"Fraction and radical templates" on the EE toolbar (second from the left on
the bottom row).
If it's (c), you can find it in the "Operator symbols" palette (fourth from
the left on the top row); or use character 00F7 in the Latin-1 character set
in the Insert | Symbol dialog in Word.