PF migration

Hi i am doing transition of exchange 2007 to exchange 2013

i am migrating public folders from exchange 2007 to exchange 2013, I am confused here please guide me.
What does Mailbox1 mean

[PS] E:\PFExchange2013>.\PublicFolderToMailboxMapGenerator.ps1 1GB PFStat.csv FolderToMailbox.csv
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When i Open FolderToMailbox.csv i can see 
TargetMailbox,"FolderPath"
Mailbox1,"\"
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I have created a new public folder
[PS] C:\Windows\System32>New-Mailbox -PublicFolder MYPUBFOlder -Database DB01 -HoldForMigration: $true
How to associate Mailbox1 with MYPUBFOlder
Should i make MYPUBFolder to default PublicFolder
Please do guide me with the steps as i never worked on public folders and i am confused here.