The link above will take you to the Federal Business Opportunities site (aka "FedBizOpps", formerly EPS). FedBizOpps has two primary features: a central government-wide index, and an application that allows buyers to post notice of procurements, directly, to the internet.
CBDNet has been deprecated in favor of FedBizOpps, above. FedBizOpps will have everything CBDNet has, plus additional important information.