Well first of all to make money you need to have traffic Modalitys of making money Affiliates Adsense or similar programs Selling yourself advertisments Regards
For newbies, just put adsense or bidvertiser. After you've received your first check, find other types of ads to run on your websites.
your primary focus should be getting backlinks, SEO, which will in time bring some traffic. without traffic, you are not making any. once you start getting traffic, you can put adsense code on your site which wil make you some money
Concentrate of getting backlinks and promote yur sites like crazy in forums and social bookmarks. More tarffic equals more money especially if you use PPC advertisement for your sites.
the best way to earn money if you have many visitors to your site is to put adsense in your sites because they pay high per click more than other companies