Thank you for this turorial 4u2ges.
I am trying to follow it and it seems i could keep up up to some point.
But when you say "Select loop vertices" it looks different here.
I cannot select the vertices like your are doing. I am pressing 'C' and then dragging the circle down.

Do you have an idea what i could have done wrong or which step i could have missed?
Or should i rather start over again.
Thanks for all your help.
EDIT: i thought that up to this point everything should have been correct: