If you are using tinymce editor for content creation/editing, you can use the resource browser to upload images for usage (if you have the proper permissions).
With the document open for edit, click the Image insert icon on the tinymce toolbar.
On the tab thats open when the window opens, at the far right of the Image url input, click that icon, which will open up the resource browser.
You can then browse whats available, create a new folder or upload an image to use.
Hope this helps
