Adding border to a specific section ...

[Robert Maxwell]

Hello. I am creating this banner for a website. The left container is empty i.e., white area. I want to create a thin line as border of it. Tried using the rectangle tool and applying border of it but all in vain. 

Can someone from community please help?

Thanks!

[c.pfaffenbichler]

I think 

• Select > All 

• Select > Modify > Contract 

• Select > Inverse 

• Layer > New Fill Layer > Solid Color 

would be an option.