If you want to know for sure, you can ask the dealer what they use. It would be good to know for the future anyway.
There are two main types of anti freeze, generally they all use ethylene glycol as the coolant base; though they differ in the type of corrosion inhibitors used. "Traditional" coolants (often green or yellow) generally use silicates, while "new style" (generally orange or pink) coolants use organic acids. GM's DexCool is an example of a newer organic acid coolant. These two types shouldn't be mixed if possible, as the effectiveness of the corrosion inhibitors can be reduced.
Unfortunately, checking the color of the existing coolant in the expansion tank isn't good enough to confirm a match against what you bought.
That said, if you merely need to top up the expansion bottle, you may be able to get away with adding only distilled water, which would be compatible with any coolant. Check the coolant concentration with a hydrometer, and if you've got sufficient coolant concentration, you can simply add water.
For what it's worth, apparently someone from the SAE (Society of Automotive Engineers) said you can safely mix up to 15% of the traditional coolant type into an organic acid type coolant without much of an effect on the corrosion inhibitors. I'd still avoid it if possible. I've personally seen brown sludgey coolant resulting from mixing traditional coolant into VW/Audi's organic acid coolant.