In Access the hyperlink data type is a actually a text string with three parts separated with a #.


Example:

Display Text Here#http://www.hitechcoach.com.com#Sub address here
When you add data to a Hyperlink field directly, you must include the two # symbols to delimit the parts of the hyperlink data.

I would use an update query to update Column 12 with the data in Column 11 wrapped with the #.

Example:
UPDATE [My Table Name] SET [Column12] = "#" & [Columne11] & "#"

ALERT: Make a backup of the database before running any Update Query!


Also look int he help for:
HyperlinkPart Method