Comsol multiphysics problem

[Boryna]

Dear Friends,

I am totally new in Comsol Multiphysics and I can't manage with following problem:

I have to subdomains (2D). In the first one convection-diffusion transport occurs, and in the second one only diffusion. Despite of the process is 2D I need to specify following boundary condition on the boundary between subdomains:

e D dC1/dy = D dC2/dy

where
e - efficiency coefficient
D - diffusion coefficient
C1 - concentration in diffusion subdomain
C2 - concentration in convection diffusion subdomain

I use Comsol 3.4.
This is my first model in Comsol so pretty lost :)

Thank You in advance!
Szymon