I'm new at this . Messed up by placing two Saitos in the 2 cycle catagory, and then putting an OS in the 4 Stroke catagory.
How can I correct this?

You can change the category your ad is in by using the Edit tool located to the right of the ad listing on the My Ads page in the My Market area of the marketplace. Go through the tool to Step 5 where categories are selected. Remove the existing category, then select the correct one. Once you do this, resubmit your ad and it will be listed in the new category.