Defining key with phpmyadmin


Please tell me if I am going about this all wrong…

I’m coming from using arrays so this is a little different as the DB doesnt auto generate IDs for me…

So I have a DB with a couple of columns, thats all sweet. What I want to do, is add some kind of numbering system, an automatic one of course. I think this is called defining the ‘key’ but I can not work out how to do this with phpMyAdmin? Can anyone help?

And secondly, say I delete an item or row, will this automatically patch the numbers, like when you splice an array? Or do I have to do this manually?