How Much Time Do I Need To Spend?

I have recently been seeing a lot of ads on websites that link to different related products. From what I understand, the people who put up these pages get paid when people click on the ads and go to the sites where these products are sold. I was told this was called affiliate marketing, and that you can join a company and do it from home, which is one of the benefits of affiliate marketing. But I am worried I might not have enough time. How much time do you need to spend in order to do this? Is there a minimum amount of time you need to spend making these websites with links?