create a rectangle
choose outline
large enough for the frame
adapt all this to the frame
 

create rectangles along the frame
this only serves as a spacer for the photo
this should be open at the top
at the sides and bottom it is sufficient if it is 2cm thick

again a rectangle
for the rectangle in the middle it is important to use the same thickness as the exception under the frame
the height of the small rectangle is as thick as the wood including the kerf

arrange the flowers the way you like it
then select this and choose outline
select the outline and the frame and choose unite