If you wish to upload images to use on your website you can do this by going to the advanced editor on one of your sites then selecting the upload images option. Simply browse for the file on your computer and click on the upload button; this will then upload the image to your website. Once the file is uploaded you will see the details regarding the newly uploaded image at the bottom of the page along with the code to use to add it to your website, (Try creating a new inside header and adding this code to it to see how it works).
Please note that if you wish to host images for use on other websites (such as banner exchanges) you will need to obtain some 3rd party web hosting. If you are looking to purchase web hosting we can recommend www.ixwebhosting.com as they provide live chat support, alternatively free web hosting can be found in many places on the internet.