Joomla 3.0 - Adding Embedded Images from the Front-end of the Website
Login by clicking on the "Admin" button at the top of the site or the "Login" link at the very bottom of the homepage.
joomla frontend editor for admins
Enter your username and password and login.
Joomla Login Form
Go to the page you wish to edit. 
In the upper right corner there will be and "edit" link.  Edit Joomla Articles
It could also be a pencil & paper icon in the upper right corner.
Any articles that are available for you to make changes to. Click on that to begin editing that page. 
This is what your editor may look like.
Joomla 3.0 Front End Article Editor
To add an image, place your cursor where you want the image to be and then click on the "image" image button jooma 3.0 button at the bottom of the editor window.
When you click on that button a pop up window will appear. You can select an image already on your site or upload a new image.
Joomla 3.0 Media Manager Front End 
Be sure to resize your images in advance using this online resizing tool. The images should be no larger than 1000 pixels wide and the resolution should be set to 72 dpi.
You can either select the image you want to use or you can upload your own images by clicking on "Choose Files" and browsing your computer for your resized images.
Choose Files Website Editing Tutorials
Select the one you want to use and click "Open". You will see your filename in the field. Then click the blue "Start Upload" button.
Select the image you want by clicking on it once. Give it an "Image Description" that is keyword rich. This wont be visible on your site, it tells search engines what the image is of. The image title is optional.
always give images descriptions in website design
Once you've given it a description click "Insert" in the upper right corner of the pop-up window.
joomla image inserting tutorials by Knightling web design
When you've uploaded the image you will see it on the page. You may want to select your image and click on the left, center or right align icon at the top of the editor window.
aligning objects in joomla 3.0
You may type in more content or simply save the article by clicking "Save" in the upper right corner. Your updates will immediately appear on the site. If you do not see your changes please refresh your browser. 
Save joomla website edits
Always be sure to logout when you have completed your website updates. To do so click on the "Admin" button or "Login" link at the footer again and click on the "LOGOUT" button.
Logout of the frontend of joomla