OK… I think it can be a little bit difficult.
At first, please check that you use the correct slicer. Please use the “CuraEngine” not the “Slic3r”.
With installation of the Vertex Nono repetier software the slice “slic3r” have not the correct parameter for printing with the Nano.
Then please check the filament diameter (at the filament page). 1.75mm is correct.
Then please check the Qualify parameter that the layer height have the correct parameters (at the Speed and Quality page).
The please check the nozzle diameter are correct (at extrusion page).
And at last please check the shell thickness (at Structure page). The best is it they have a multiple of the nozzle diameter. For example for a worst case: Nozzle 0.4mm and shell thickness 0.6mm!
Please check this all at first.
Greetings from Berlin at night.