User input row and column size for a 2-D array with Random numbers filling it C#

Hi I am very new to coding and was trying to figure out how to create a 2d array. That asks the user to input row and column size than fills those chosen row and column sizes with random numbers. After days of trying to figure it out I decided to come on here for help. Here is what I have so far, its all over the places I KNOW.

                char row = 'i';
                char column = 'j';
                int[,] twoDarray = new int[row, column];
                
                int min = 0;
                int max = 100;
                Random randNum = new Random();
                for (int i = 0; i < twoDarray.Length; ++i)
                
                for (int j = 0; j < twoDarray.Length; ++j) 
                
                {
                   twoDarray[i, j] = Convert.ToInt32(In.ReadLine());
                }