、。
When you wake up tomorrow morning, you'll find something wonderful.
Literal
Tomorrow [possessive-の] morning wake-up [conditional-たら], wonderful thing [subject-が] be-found [assertive-よ].
~たら is a conditional/temporal 'when/if' form — neutral between conditional and sequential meanings. Here it's closer to 'when you wake up' than 'if you wake up.' 見つかる is the intransitive counterpart of 見つける: 'to be found / to turn up,' not 'to search for.' The final よ adds assurance, like a parent leaving a surprise for a child.