After you've extracted the files, I think, the easiest way to import shapefile is to use the Oracle MapBuilder tool. Under the tools menu, you'll find the Import shapefile item. After that, I think it's pretty straightforward :).
I suggest you to use MapBuilder. It can "batch-import" your shapefiles (so you don't have to do it one-by-one using shp2sdo), and it creates the metadata, and spatial index too.
Here you can find MapBuilder: http://www.oracle.com/technology/software/products/mapviewer/index.html
Extract the files, and start mapbuilder.jar (it has a GUI). Connect to your database, and after that, under the Tools menu, select the Import shapefile item. There you'll find the batch import option.