A meditative state to me, is one that your mind is not on conscience thoughts. You want to feel what is not felt by the conscience mind. ie: I feel my fingers touching the keyboard as I type, if I was in a meditative state, I might (not typing but my fingers on the keyboard for this example) feel the keyboard touching my fingers or the space between the keyboard and my fingers. Sounds simplistic, but try it.
And what do I think about ? nothing. As soon as a thought enters my brain I tell it to leave. Soon I reach a state that I am not conscience of thoughts entering my mind.
How is it done? Each will have a system that works for them. Some, it is quietness, others like myself like music to help me focus the music out so I am no longer conscience of it (this is done by me going "into" the music.
It is hard to acheive the place we are talking about, but I do know this, once you have gotten there, you know you arrived when you come out.
The answers you receive will all be differant, yet there will be a universal sameness. :o)