I'd like to promote our website by placing an article about similar products and services as ours. Tell the history how it was invented, how it was developed, etc. We produce and offer software thus I believe it would be interesting article to a wide audience. At the end of the article I'm going to place a link to us.
Can you please let me know where I can place such an article for free? How should I search for it?
Depends on your agreement with the first company. They may want exclusive rights to it and if they do you can't resell it or post it elsewhere.
Is there a difference between when I work for a company to write articles and writing individual articles then selling it to them? I'm thinking of the latter one that I could sell my articles to different companies.
What about Intellectual Property Rights? Although the company has published it, I have written it with my own knowledge.