On your profile page, you should see five menus labelled "Create" "Organize" "Read" "Explore" "Shop". Under the "Create" menu, one of the items is "Upload Images". Click that, then drag and drop or use the "choose files" button.

You can set privacy levels under "Manage Images" under the "Organize" menu option. Choose "View your images" to get to the page that shows the links you can use to post an image or a thumbnail in a post.