how to navigate to other portlet

hi all,

i have two portlets, in first portlet, having different controls(user form details information) and next button, after user selected or fill the form in first portlet and click next button should navigate to the next portlet, in second portlet also have some controls and back button and next button, after filling of information or selecting the control choices in second portlet if user click back button should navigate to the first portlet with previous filled information in first portlet, please sugget me how to achieve this in portlets.

anil kuma e