How to import images

How do I import an image or clip art and make adjustments or edit the imported image.
I have gone as far as importing the image, but I don’t see it in the window. Also, does the image have to have a certain extension? I am using vers 2.72 with windows 8.1

In the UV/Image Editor window you can open images (Image / Open Image menu)
For importing .svg files you can enable the svg importer in the .svg importer addon in the User Preferences / Addon panel if it does not show up under the File / Import menu

What are you using this image for ?

What do you want to do with the image?
If you want to import the image and use it as a model, you can go to file>user preferences>addons, search for “import images as planes”, enable it, got to file>import>images as planes, and there you have it.

If you just want to make some adjustments to the image, you can go to the node editor,
(make sure you click on compositing, and use nodes)
shift-A, input>image/movie clip/ whatever.

If you want to use the image as a background, go to the right panel in the 3d view, enable “background images”, add image, and change axis to camera.