Is it on your phone or on your computer?
If on computer, go to
http://www.imgur.com
At the top right of this page is a bit that says Upload Images
with two buttons (Computer and the other Web).
Click the computer button and a dialogue should open for you to navigate to where your picture is, click OK.
Then after that click the Upload button.
After this you will be brought to a new page with your picture.
Right click the picture and select "Copy Shortcut"
Now on your new post, just paste the shortcut URL between the {img}{/img} (square brackets though, no the cutsey brackets) tags.