How to focus properly

[dmcd10]

I have a canon A2100 digital camera
It has a green box that comes up on screen that shows were the camera will focus
my problem is, that the box isnt always were I want the camera to focus eg it may be in the middle and I want to eg have the photo in the screen, but focus on the flower in the left hand corner
can someone please tell me how I can do this? or if its possible? thank you

 

[cin19]

For your case, you can move the focus box point to the subject, then pressed the shutter button half way down. And hold this position, then moved the camera and recomposed the picture than you like. Now you can all the way pressed the shutter button to take the picture.

Good luck.