The step-by-step instructions might differ depending on the version of
Excel you are using, but hopefully this gets you close.
Suppose your list of names is in column A. Next to the first name, in
column B, put
=RAND()
Fill this formula down to the last name. This will generate a random
number essentially between 0 and 1 on every row.
With the cursor still in column B, use Data | Sort. The sort dialog will
suggest you sort on column B ascending (you may wish to twiddle with the
"my data range has header row | no header row" setting). Click OK.
Your names will now be "sorted" by a random number.
This might look a little confusing at first because the RAND function
will recalculate when you do this... and the random numbers will no
longer be sorted. If you want to fix the random number values
permanently, select them, copy, then Edit | Paste Special, tick Values,
and OK.
Hope this helps!