I read somewhere that Adsense cannot be placed on a free website. I have made a website at blogger which is free. Can i still use Adsense on it?
yes but the quality of your site must be good in order to get accepted. Sites on freewebs generally are poor in quality. If you've already been approved, then you can use it wherever but most new adsense users have a hard time getting accepted because the sites they submit to Adsense are low in quality or content.
If your free web service provider has their own Google Adsense on your site, then you cannot post yours as well.