Well step one. You have to find space on the WWW somewhere to palce the picture. Most ISP give you webspace when you sign up for your internet account. Its usually allocated by default. Have a lok at your account and see if you ahve webspace.
If you dont have your own webspace then you could sign up for free webspace somewhere. Or you could sign up for a fotopic account.. but it seems a little overkill for one picture
No point even starting to explain how to upload until you have a space somewhere to place the picture.
However if you go for a fotopic account.. you can use there control panel to upload your picture :0