Thicken surface problems

Hello everyone!

I'm a student, and i'm busy with my own hobby project at the moment.
But the problem is that i can't thicken some surface's.
And also i don't know what the problem is.
It gives an error (unable to thicken the surface).
I have also tried this:
- offset surface and make that thicken but the problem is that i get only the half thicken.

My wish:
I want to thicken the surface and at some nice fillet.

My english isn't very well..