Sure. Start a new post (or edit an existing one). Underneath the window in which you type is a button saying 'go advanced' click it. It will open up further options which appear below the button (you may need to scroll down). Find the 'manage attachments' button and click it. It will open a pop up window (make sure you allow pop-ups from this site in your browser). Click the browse button and find your image on your puter. Once you have selected it, click upload.