Hi,
I haven't really worked with MIKE11 so i just know some sort of workaround. Do you have MIKE HYDRO? In this case you can add Shapefiles as Background Layers and afterwards open the menu Tools > Auto generate Cross Sections and choose "Survey points from shape file". Now you can select the shapefile you added as Background Layer in the step before. The cross section shapefile should be a point shapefile with a field that defines which survey point belongs to which cross section number.
The river network can be imported in MIKE HYDRO by File > Import from shape file and then choose "Branches".
Hope this helps!