Two thoughts, meant seriously-not flippantly.

Go to a parts store and ask.  The counter guys usually know how the
arms mount-demount on the drive post for most rides.

Look on the back of some wiper arm packages at local KMart/WalMart,
etc.  The usually print out installation instructions.  Anco does a
pretty good job of instructing.

In general, there is a small lever at the base of the arm that either
must be slid out to "unlock" the arm from the post, or be be pressed
down to release the arm.  Look for that.