What are we supposed to do while meditating?

Yes I have meditated and I have searched the Internet this question before landing here, what I describe below is a mixture of what I have read of what one should do during meditation and what actually happens when I actually meditate. Most of the articles I have found say that try to keep focus but here I want to ask is what do I focus upon ? My problems, my desires or just how do we keep focus without a subject to feed upon ? And while meditating I have found my thoughts wander away and keep reminding myself by repeating mentally "no I am meditating, no I am meditating". Is that the right method ? but the biggest question is when we say focus(in any other field apart from meditation) we understand it in general context as to improve our performance or invest ourselves more in that field but what does it mean in meditation, is it repeating a thought continuously in our head or something else ? While some other articles say watch the thoughts as they occur , I mean okay I could watch the thoughts that occur during a meditation session but then doesn't that seem a little contradictory ? You are producing the thoughts and then you are seeing that occur so then actually we could guide our thoughts then, why does it then say stay and observe ? I know above I have asked my questions in a hodgepodge manner so let me sum it up succinctly: - **What are we supposed to think during meditation or we do not need to think at all ?** - **Generally do we set timers for meditation sessions or do we get an intuitive feel that I can't focus or meditate any more for today ?**