Robinfur's quest: After you gave him poppy seeds talk to him again and type Y/Yes when he asks "Do you really want to help?" Then talk to him at the medicine cat healing nests AT NIGHT(If you don't know where that place is go to the Fireclan cave and click on the right hole)After he says something about Cold Stone and Firestar you can choose one of these options to get to the cold stone:
1.Become a full medicine cat(I advice you to use the second way because this one takes too much time)
2.Kill the cold stone guards with deathberries.
It's NECESSARY to be a medicine cat apprentice since Lunarclaw won't let you take any deathberries.
After the prophecy you got from the place of cold waters go back to Robinfur and then sleep you should get a nightmare with Firestar.
These are the places Firestar appears in the nightmare:
1.Breezestar's den.
2.Next to Plumclaw.
3.Near the dens.
After you find all three Firestar's silhouettes talk to Robinfur and you're done.