you will need to crack the manual, read a book, or check out podcasts on each topic.
Step 1 Select the flowers (there are several ways to make a selection, from Magic Wand, to Quick Selection Tool, to Channels). I cover many of them in Understanding Adobe Photoshop Book and Podcast. As do most photoshop books.
Step 2 Inverse Selection (look it up in Help. just a menu command)
Step 3 Adjsutment Layers (again... see above).
What you are asking is easy... but you can't expect a forum to replace looking up basic techniques once someone tells you which ones you need to use.
Richard M. Harrington, PMP
Author: Photoshop for Video, Understanding Adobe Photoshop, and ATS:iWork