[Dev-luatex] variable

[and at linux.pl]

Hello,

Anybody know how I can set variable in tex?

For example

\count10=20
\def\proste{To jest prosty napis}
  a\directlua{tex.print(tex.count[10]+5)}b
  a\directlua{tex.set("\proste","Trudne")}b
\proste
\bye

I need setup \proste definition to my own string

How I can read TeX variable \mynumber from lua
and set variable \mynumber on TeX but set in lua script.

Thanks
Janusz Biznesu