Try looking for your header.php and then look for title drop a line down and insert your tags.You want the header out the language folder.I never used yahoo store but this is usally the way.Good hunting
Found this sorry did not know you had o back end.While the Keywords field also appears in the "Variables" section of Editor 3.0, meta tag information entered here will only be applied to the store's entry page. Keywords and descriptions can be applied to each page of a store on a page-by-page basis. To enter keywords for individual pages: 1.In Store Editor, navigate to the store page for which you'd like to enter keywords.2.Choose "Edit" from the Editor toolbar.3.Enter keywords for this page in the Keywords field.4.Click the Update button to save your keywords.5.Repeat steps 1 through 4 for each page you'd like to apply keywords to.6.Publish your changes in Store Editor. To enter descriptions for individual pages: 1.In Store Editor, navigate to the store page for which you'd like to enter a description.2.Choose "Edit" from the Editor toolbar.3.Enter the description for this page in the Description field.4.Click the Update button to save the page description.5.Repeat steps 1 through 4 for each page you'd like to apply a description to.6.Publish your changes in Store Editor.