A friend of mine had some trouble setting up the homepage banners with OpenCart so i thought i would share my instructions on how to setup homepage banners.
You need to upload your banner to start with so in the admin go to System > Design > Banners. When loaded click on Insert.
Name your banner and simply upload it then press save at the top.
Head back the menu and click Extensions > Modules.
Now find the Slideshow module and click edit.
Once loaded press Add Module then select the banner you uploaded, enter dimensions, choose layout as Home and set the sort order.
Now your banner will be showing!