1) The wireless modem card should look like this:

2) To install, first disconnect the power by pulling out the power cable from the back of the modem.

Then remove the rubber plug from the top of the case.

3) Next, insert the wireless card.
It needs to be pushed in quite firmly.

(If card cannot be inserted fully so that the shiny metal part almost disappears, try flipping it around the other way.)

4) When fully inserted the two small lights should be just visible above the case.

Reconnect the power and...

5) The hard part's done!

The lights on the modem card should now be on.

6) Relax two or three minutes while the modem re-starts.