Heres a video about how to add a new image to a wordpress page or post.
Images that you’ve previously uploaded to your site are stored in your media library.
Adding image to a post or page from your media library is as simple as:
1. Place your cursor where you would like the image to be inserted.
2. Click on Add An Image icon (located on right of Upload/Insert above your Editor).
Add an image icon
3. Clcik on the Media Library tab and then on Images.
4. Locate the image you wish to insert and click its Show link.
Click on Show next to the image you want to insert
5. Now you just need to:
type a title for the image
add alternate text
choose how you want the image align (None, Left, Center or Right)
select size of image you want to insert (Thumbnail, Medium, Large or Full Size)
and then click Insert into Post
Editing image information before inserting into a post