Blog networks: You can find offers on this forum under "SEO - Link Building" section.
Automatic content: There are tools available for creating content automatically, based on a list of topics. However, the quality of such articles are not going to be good enough usually to compete with in competitive niches. I would rather have somebody to write my content, because that will surely result much better quality (although, it may depend on your goal with these articles).
Based on your questions, my advice to you is to look around first, start learning and understanding how things are being done in the safe way before taking any action. Otherwise, it can easily backfire and you will find yourself penalized by the SERP.