I am trying to create a Hasse diagram , which has 3 minimal elements and 3 maximal elements, but it every element is either small than exactly 2 elements or bigger than exactly two elements
My solution to this is 
But I am concerned , that it is wrong because number six is greater than all of them, so it can be said that it is not greater that two elements, although I have connected it to only 2 elements. Is my solution right or wrong?
The fact that the number $6$ is greater than all other numbers with respect to the usual total order of integers is irrelevant for your exercise. You are only using the numbers as symbols for the six elements of the poset. You could have used $\clubsuit$, $\diamondsuit$, $\heartsuit$, $\spadesuit$, $\triangle$ and $\square$ instead of $1$, $2$, $3$, $4$, $5$ and $6$.