Simply assume that your products are already listed without images: -
Now upload your images to media/import, in case you do not have a folder yet named “import” within your media simply create one.
Log onto the admin area of magento.
Now click system > import/export > dataflows – profiles
Click add new profile
Now here’s the screen that you will be presented with (click on the image for a larger version) : -
Make sure that the “enclosed values in” field is left blank. Now under the heading “filed mapping”, put the image category as required by you, this example is very basic just to give you an idea. You can also add categories such as image labels, all the choices appear in the dropdown menus every time you add a new item. Be sure to add “sku” as mgento uses this given value as the producer unique identifier.
Save your new configuration
Create a new CSV file in your normal editor like Excel for example. Create columns for every field that you created in dataflow. i.e. sku, image, thumbnail etc. You can now list your sku number in the appropriate column and also input your image titles. Just be sure that the image names begin with /as in “/web-design.jpg”
After all the details are complete you can now save your CSV and return back to magento. Within the dataflow profile as created by you, click “upload file” after that select that and click “save and continue edit”.
And finally click on the “run profile” tab. From the dropdown menu select the file that you have uploaded and click “run profile in popup”. Magento should do the rest for you.
For more information visit : http://ilovemage.com/learn/