in my wordpress admin while publishing a post i found they are advanced options.what is the use of this options all in one seo,excerpt,trackbacks,comments and pings,custom fields etc ?
They are basically there for your use, but you can ignore anything that you dont want. You can rename uncategorised to a category name that you want instead.
When you login, click manage > categories > uncategorized, after clicking on uncategorized just type in the new name in Category Name.