Can i add an upload button for visitors to upload their photos?

I presume that you are referring to Blogger and that you want people to upload their photos to your blog. Since the only person authorised to modify or edit your blog is you (and anyone else you choose specifically), except in the comments section, which accepts text only, there is no way that visitors can upload their photos so that they show on the page. The only possible way would be for visitors to paste the URL to their photos on Flickr, Photobox or whatever into their comments.