If you don’t have Facebook application installed on iPhone then first install it. Run App Store from your iPhone and Search for Facebook. To install tap on FREE.
Once you have installed the Facebook Application, run the Facebook application and enter your login detail.
Tap on Camera icon and then Choose Existing Photo button if you have already photos in iPhone.
If you select Take Photo, the camera function will be enabled and you can take your photo then tap Use Photo.
Select a photo from you Camera Roll or Photo Library.
write a caption for the photo and press Upload button, this photo will be posted on Facebook from your iPhone and added to Facebook Mobile Uploads
That’s all, Now you can upload photos from iPhone to Facebook.