Hi,
You need to set the WHERE condition property of the repeater to appropriate value. You could use for example following query macro, that takes the URL parameter category and inserts it into the WHERE condition, if there is no category parameter in the URL, value 1 will be used:
WHERE condition:
Category={%category|(default)1%}More information about
macro expressions can be found in Developer's guide.
Best regards,
Michal Legen