I am not sure what your table represents, but I thin k I can help you sort out the problems.
When you throw 2 typical (and fair) dice there are 36 possible outcomes, i.e. the sample space contains 36 points.
The easiest way to answer the questions you have is to write out the samples space as a square table, with 1 to 6 down the side and across the top. Write the sum of the faces in the square at each intersection. Now just count up the number of squares which satisfy the question and divide by 36 to get your probability.
P.S.
It is not too difficult to get the distribution function for the sum of 2 random variables with identical and uniform distributions, but you really do not need that for this problem. If you want that distribution, please send me a message and I wll try to figure out how to send it to you.
