You have to get the mirror from Aphrodite after you beat the Hydra and Cerberus. After, Hercules will help you.
If you mean the Muses. There are 5 not 3 but the singers are, Lillias White, Vaneese Thomas, Cheryl Freeman, LaChanze & Roz Ryan.
Hercules had impressed Helios with his daring boldness.
muses
In order to move the rock on Mythology Island in Poptropica, you need to find Hercules, who is located in the Hercules' Hero Hut area. Hercules will lend you his strength and help you move the rock.
At the almost end of the island Zeus will steel all of the sacred items then you tell Hercules that and he will help you.
Hercules wont listen till Zeus steals all of the items when he does you go to Hercules and then he'll help you.
Get all the items and bring them to Athena. She will tell you that Hercules will help you and then Hercules will help you push the rock.
The muses are in the temple of Apollo.
The Muses Are Heard was created in 1956.
Once Zeus has stolen all the sacred items from you Hercules will help you. So you the magic mirror to teleport both of you there.
All Muses are female.