Well, I am a new blogger.I have started two month ago.I have been posting article on online money making resources and reviews.But now, I want to make my Niche a little wider by posting blogger resources items. Will it harm my indexing in search engines?
Concentrating on a specific niche may be easier to get rankings. That way Google would see all of your pages targeting pages related to your other keywords. If your topic is too wide Google doesn't know what your site really focuses on. Say your topic is dogs and you have pages called dog-training, dog-breeds, dog-care, etc. Then it is very obvious to Google that your site is all about dogs. Since each page has something about dogs in the url and title, that may help the other internal pages that that page links to. If you also had a page about cats, theoretically that page shouldn't help the other dog pages as much. It is questionable whether Google can distinguish different themes, but it should help to have related keywords in the pages that link to you...including your internal pages.
Have you considered making a 2nd blog about webmaster resources? You may have a better chance of success by having 2 different blogs with a separate theme.