Ecommerce BackLinks and URL

Hi everyone,
I have a skateboard ecommerce and I have already start with backlinks, creating me a big doubt.

for example:

I have the KW - "vans tshirt" ranking on 14th to the URL: domain.com/vans.html

I have the domain.com/vans/tshirt.html URL but the KW "vans tshirt" is ranking for domain.com/vans.html

Should I give the backlink to domain.com/vans/tshirt.html or domain.com/vans.html ?

Thanks All!!