If you want to create a blog then go to www.blogger.com and create a blog first.
1.Creating a blog is very easy.
2.Then Add atleast 15 Posts to it.
3.Then go to www.adsense.com and sign up for Google Adsense, but first you must follow the conditions below
4.There are other Affiliate companies like Smowtion,Chitika,Infolinks,Kontera etc.
Smowtion Ads: Go to www.smowtion.com and Sign up for Smowtion Ads.
Chitika Ads: www.chitika.com
Sign Up for above Affiliate Companies and keep the best Affiliate Company Ads to your blog.
How To Create A Website/Own a Custom Domain?
If you want,then you can Own a Custom Domain in the "Settings" Option in www.blogger.com , they'll charge you $10(approx) per year.Then you will be owning your own domain.
For Eg: If you name your blog (www.example.blogspot.com) then after you own the domain it'll be (www.example.com).
Or You can go to sites like www.bigrock.com and there you can create your own website for approx. $9 per year.