Images are governed by copyright law. In most cases you would not be able to upload images, unless you own the copyright, you have explicit permission from the publisher, or a copyright statement or licence permits this.
Copyright in the photographs remains with the photographer. You would need to contact them to request permission. The site gives contact information and you are advised to give as much information as possible about yourself, the photo, and how you want to use it.
Google Image Search is a tool for finding pictures available from anywhere on the internet, it is not a database of images owned by Google. You should not upload copies of images unless you have explicit permission from the publisher (the person, or body who created the image), or a copyright statement or licence on the web page specifically permits this.
Some images may be uploaded and other may not, according to the permissions assigned by the copyright owner. Images on Wikipedia will usually be tagged with the source of the image and and copyright permissions. Click on the picture to see this information. If permission is not explicitly given, do not upload the image.
Microsoft Office users using newer versions of Microsoft Office will no longer have Clip Art, an image library found in legacy versions. Instead, inserting an 'Online Picture' and this will enable to your search the web for a suitable image. More information can be located on the Microsoft website.