You can fill a 6x6 table with the outcomes and then find the probabilities of a given outcome by counting the number of identical outcomes relative to the the number of total outcomes. For example, the result of rolling a pair of 1's is (1 + 1) / 3 = 2/3. Of the 36 possible outcomes, this is the only cell in the table with 2/3 as the outcome, thus having a probability of 1/36. You can follow this same procedure for all the other cells to come up with the distribution.