what are the steps should be taken before hosting ?

i have created a website in asp.net c#. Now I want to know what step should be taken before hosting it to the internet or before purchasing domain. I mean about the security of my website and may i able to make changes to the site  during running?

 

Sorry for the english. i am beginner in asp.net c# i just want to learn these things. please sir/mam give me instructions about this.