There are many affiliate programs that offer some level of training with regard to promoting a business online. When you join, the company will assign your affiliate ID and give you a link to your own sales page so that you can actually start advertising on day one. You can start earning commissions while you are still learning how! However, it is probably a good idea to read over the documentation on the site. This will give you ideas on what to say in your blog, ads, etc..
Affiliate marketing is very attractive, especially as a first effort to start a home business online. This is so in large part because they provide everything you need to get started on the first day. There is really no reason to wait. If they don’t have official training, then read all the FAQs and other documentation in your member back office.
An affiliate program has the product ready for you. They allow you to earn money from their intellectual property. This has taken them possibly years and many dollars to develop. There are also costs they pay associated with running the membership program. This is why when you become a member you will eventually pay a monthly membership fee. What you get in return is far and above more than you will pay. If you were to pay for a website, a web page, maintaining software, hosting, etc. you will realize how much time and money you save by affiliating yourself with an existing company.
It can take a while where you are learning and advertising, and it may be unlikely as a beginner that you will make sales the first day. It is possible though so why not dive right in as it will probably take some time to see substantial results.
However usually when you see statements that you can make money today it assumes you have a list of existing customers or prospects -or at the very least marketing experience.
Unfortunately there is no magic that will create sales. You have to promote your links constantly over time to build momentum. What they are actually saying is that it is possible to START the process to earn money; meaning at the least to become a member and start the process of developing your business today.