What to do after publishing a website?

Now I've created my website and have published it on the net. what to do next? I mean, how can i introduce my site to search engines, and if there is any other step?

I googled about it, but i can't find a complete guide. there are many sites explaining the "Enter your URL below and click Submit!", but i know there is much more context. I've heard something about robots.txt and googled7a34dccBlahBlah.html files and so on, but i don't know what to do exactly.

Can you help me?