Underlining

I am trying to underline text. However, the
underlined "U" icon is missing from my toolbar. I still
have the "B" for bold and the "I" for Italic, but
no "U"! My so-called help function tells me to select
the text I wish to underline, go to the formatting
toolbar and select underlined U. I have "Format" on my
toolbar but not "formatting." There is no underlined U
on my format menu. The dear folks at Microsoft,
apparently feeling a little pressed for cash and not
thinking that the $450 I paid for this software is
enough, want over $200 more to tell me how it works!!!
Can someone tell me how to underline text?