This is done inside your Media Manager in Visage
Once you have your Media Manager open, select which folder you wish to upload an image into and then click on Upload:
A Box will appear where you can either Drag images or browse for images;
There is a list of Valid Extensions, so you can ensure you upload an image that is accepted in Visage.
Valid extensions: gif, jpg, htm, html, pdf, zip, txt, php, png, swf, dcr, mov, qt, ram, rm, avi, mpg, mpeg, asf, flv, doc, docx, xls, xlsx, odt, ods, wmv
Once you have added the image/s you want to upload you will need to click 'Upload'
Once the file has been uploaded to the server you can click Close