I was just wondering if you needed to enter a bonus code in order to claim this bonus.

The bonus should ideally be issued automatically with the first deposit without the need to enter the bonus code.
However unfortunately it wasn't automatically issued in your account and was manually added.
The bonus consists of 4 slabs of $25 each and to release each slab you would have to earn 100 loyalty points.
The first slab of $25 was released yesterday based on the points you had earned since making the deposit.
Once added the details can be checked in the client under: Rewards> Bonus> Active bonus.
Kind regards,

Party_Rep
http://nj.partypoker.com, twitter: @partypokerUS
Email : support.nj@partypoker.com , Phone : 877 448-5831 (Toll free)