You need to use RelativeURls as Sergey mentioned and only for more information you can refer the following example:
Website
AdminFolder
SuperAdminFolder
Page2.aspx
Page3.aspx
UserFolder
SuperUserFolder
Page5.aspx
Page4.aspx
Page1.aspx
To access to Page3 from Page2 you can use "../Page3.aspx" As the path
To access to Page1 from Page2 you can use "~/Page1.aspx" As the path
To access to Page5 from Page2 you can use "../../Users/SuperUser/Page5.aspx" or "~/Users/SuperUser/Page5.aspx" As the path
Basically you can play with following symbols to access your page :
“.” the current physical directory of the file (e.g. aspx) being executed
".." The parent directory
"~” The physical path to the root of the application