You probably do not have Swiss Pass Cards. The Swiss Pass Card is a red plastic card with your picture on it that is used to load commuter and discount passes on. It is a product targeted at residents.
You probably have a Swiss Travel Pass.
You can indeed pay extra for 1st class. You pay for the diffence, and since you have the STP you get a 50% reduction on that. Should be around 22,- CHF. You can get it at the station, or from the conductor on the train.