passing argument to different webdynpro projects

hai everyone

i had developed few webdynpro projects...

and i had created a tree structure and given all the link to it....

first it will display login screen... asking the user name and password then depending upto on the result it will to go next screen i.e next link i.e another project link... now i want to display the name of the user that entered in the login screen in this page....

should i pass any argument to the destination page....

how to do this...