Many software packages allow you to add information that is permanently embedded into a photo. This information is called metadata. This can be read by anyone with a software package that can read metadata. Many cameras will record in the metadata the time, date and the camera settings of each photo.
When photos are downloaded with some software packages you can automatically add more data. This can include your school, the region you live in etc. Information that must not be included is anything of a personal nature including personal email addresses and phone numbers. Discuss with your teacher what information is appropriate and what must be excluded.
These programs will allow you to add information to individual photos.
You can only access this information when using a program with this ability. You cannot see the information when you just view the image.
NB Do not crop, resize or sharpen images
Cropping and resizing images will cause confusion for people in the future. Leave all images at their original size. Avoid sharpening images as sharpening images reduces the ability of all software to make changes at a later date.