How to close called wd appl.and need to open calling wd appl.

HI Experts,

    In the two linktoaction UI elements, initially second linktoaction UI element

should be invisible whenever the user clicks on first linktoaction then another

wd appl. Will open there user need to fill some details then click on submit.

then the called wd appl.should be closed n it should open the calling wd appl.

now at this time the invisible linktoaction ui elemenet should be visible.

            Any one could you plz give me suitable solution fo this is greately appreciated...thanks in advance