Adding image to products:
Catalog > Manage Products > choose product > Images
For Slider show:
Did you install Magento with Data sample? If installing with sample data, you can find Slider show in cms home page: CMS > Pages > find home url key. In Content tab, you will see slider html.
I recommend that you should install Magento with sample data: http://devdocs.magento.com/guides/m1x/ce18-ee113/ht_magento-ce-sample.data.html
I am not sure, if you are only talking about Product image or Banner Slider of home page? I would suggest you to mention the page details.
If you facing some issues with banner, you can always choose a different extension at www.magentocommerce.com