Yup, sure can. Just boil enough water to dissolve it and then boil the solution for ~ 10 minutes to sanitize. Chill it down and pour it in. Try not to splash in order to prevent oxygen from getting in.
Has it already started fermenting? What's the style?
Yes it has. I check this morning before leaving for work and it was quite active. It is my second go at cloning Wild Bill's Orange Blossom Cream Ale. The first was great, but a little too hoppy and a bit weak on the orange.
Yeah, you'll be fine pouring it in (after boiling to sanitize and chilling). If you can, pour into a funnel with a tube that gets it below the wort's surface (in the fermenter). Don't forget to sanitize everything.