Yesterday I brewed my first batch of brown ale from a true brew kit. I followed the instructions but I think I killed the yeast. I boiled the extract for 30mins and the added it to 4 gallons of cold tap water in my primary fermented. Then I sprinkled the dry yeast on top immediately and let settle for 10 min then I stirred it in. Then I proceeded to put the cover and airlock on. when I checked the airlock 6 hours later I saw some bubbles but when I checked it this morning their was no bubbles just small air bubble attached to the airlock it self. Im not sure but I think I killed the yeast, if so can I add more yeast? Any comments will help.