Yes, what you'll need to upload is a single file with all of your lines in it, separated by a few seconds of silence. Also include a few seconds of silence if your speech is interrupted by stage directions. For example, if the script would be:
you would recordPoseidon. Are you ready?
Zeus. Yes, and you?
Poseidon. Me too. (checks watch) It is time to leave!
"Are you ready? ...[few seconds silence]... Me too ...[few seconds silence]... It is time to leave!"
Also, do remember to put a voice credit at the start of the file ("Poseidon, read by [you]").
Let me know if you have any more questions!