Pass the SelectedItems details of ListBox to another page

Question

I am working on Windows Phone 8 Application, In which, using SQLite I am showing the Database details using the ListBox to TODOLIST.xaml, I want, when I will click on any item showing in Listbox it should navigate to MainPage.xaml and on MainPage.xaml there are form which Contain the TextField for TODO, DatePicker and ListPicker for Priority, I want to show the seletected item details to those fields on MainPage.xaml.

How I can Proceed?

Xaml and CS files are attached for your reference, so easy to solve problem, in which mistakes are there, if one can made changes it will be appreciable. So please help.