Once you have uploded you photos onto flickr, click on the photo you wish. It will open a page just for that photo. Across the top will be icons. Click on send to group. This will load a list of the groups you belong to. Find the group you want to send it to (i.e. Wild About Wildlife) and click on that. Once it loads it will give you a chance to cancel or click OK. Click OK and the group should be added to a list to the right of the photo.