Currently, the government posts upcoming bills and newly passed laws to their online database, but before that, how did people find out that new laws were passed or might be passed? Some people would find out about them from the news, but how would the journalists find out about them?
Journalists find out about prospective new federal laws by talking to members of Congress and staff members (of Congressional members or committees or from the executive). This can involve official press releases or secret conversations with confidential sources. Or something in between.
Once the proposal becomes official, it's published in the online database.
Passage involves publishing to the Congressional Record, which links to the database.
Regulations passed by the executive appear in the Federal Register.
In case it's not clear, the Congressional Record and Federal Register predate the online period and are still published in paper form.
Individual states or local governments will have similar systems. However, they may not be online yet.
People could write letters to their U.S. Representative and Senators to ask specific questions. The citizens within their respective districts or states are their constituents. When telephones became widespread in society, people could telephone their U.S. Representative and Senator to ask specific questions, see A political insider's viral advice on how to make your Congress member listen; SAMPLE CONGRESSIONAL LETTER (ask very specific questions). A constituent can request a meeting with their U.S. Representative and Senators. A citizen can write to the Senate and the U.S. House of Representatives itself. The Members of Congress also have Town Hall Meetings, where you can ask questions in a public setting.
The Fourth Estate has individuals employed full-time, or otherwise independently motivated, with the charge to both pose written and vocal questions; and further investigate the concerns of the public.
The House of Rothschild used both human couriers and a carrier pigeons to facilitate communication of information, or "news", between the principals of the family, ahead of the general public, private concerns and governments.