weightpainting trouble

I have parent my character mesh to the armature.
by select mesh shift select armature hit ctrl+ P make parent to armature name groups.

When I go in pose mode select the mesh and chose weightpaint
the character is getting dark blue. In weightpainting mode I can not select any bones nothing happens? What am I doing wrong?

You have to choose the option heat bones or something like that. Not vertex groups…

Sorry I forgot to set off the button Painting mask Fkey in weight paint mode .
Now it works fine.