
As I have absolutely no experience of the powerstore, I can't really advise any more than I have already, but I bet the likes of WebAssist's Ray could do so as he has knowledge of the store's database and pages.
One other thing that might make it a bit clearer is about the tables... the structure of the two tables you need to create is what I have already suggested, but you also need to link to the products table as well for the query to work. You may have already realised this but I thought I'd say just in case. So, just to repeat myself you should have something like...
Colours table structure: colour_id; colour
ProductColours table structure: ProductColour_id; colour_id; product_id
Products table structure: product_id; product_name; product_description and so on...
It's the unique product_id number (in table Products) that will be joined to the unique colour_id number (in table Colours) via the 'joining' table of ProductColours.
Basically, you have three tables creating one sql result.
If that doesn't clear things up, and you're not getting joy here, then I suggest you post an email to the MySQL users group where there is a massive community of very experienced people who have often either answered or at least pointed me in the right direction. WebAssist seem to be good on the whole though.

Thank you very much for the information you have given above and previously, it is much appreciated. I'll certainly look at the MySQL users group.
I just need to try and get this to work in Power Store.
I'm still very much of the opinion that to be a real contender in the database shopping cart scenario, that it should offer these facilities out of the box.
Hey ho, onward and upward! Never a dull moment in computing is there?