Sorry if I come across blunt, but the fact you're asking strongly suggests that you should not attempt this for anything more than learning experience. You have the end goal - a login system - but seem to have a very limited conception of what's involved.
There are many options each with their strengths, weaknesses, and pitfalls. If you are wanting this for a live site, I concur that you should go with an existing solution that is mature.
On the other hand, learning is a good thing. I think a good first stop would be