Affiliate Marketing Secrets

Hey, I need some help with a script i’m writing for my site. I’m wanting to code a seperate page that will filter the products by the merchant.
E.g.
www.theonlinecity.co.uk/voucher-codes/…
I’ll take the merchant from the URL and query it to get the merchantId which will then form the refineby. I dont think its particularly difficult, theres some examples online using:
$oRefineBy = new stdClass()
$oRefineBy -> iId = 3
$oRefineBy -> sName = ‘MERCHANT’
But this confused me, so I’m asking if anyone can help me with this. Thanks