How to show Alert/Message OnActivate of a List Box

[#1]

I want simply to show an alert/ message on activating a list box (say LB065).

I have read the Alert section of user manual and tried creating an Alert ( say AL01)

I right click on the sheet and take properties, goes to Triggers--> sheet object event triggers where i find an option to give OnActivate actions for that object.

I am confused as to how to call this alert(say AL01) OnActivate of the list box (LB065)

Now if there is an alternate way to show an information pop up (other than normal help), then those suggestions are also welcome.