You're really almost there, aren't you? I don't understand what the problem is. You have all the code written... now you just have to put it together.

ReadAndSum()
1. sum := 0
2. input := 0
3. while input >= 0
4. do Display("The nth partial sum is ", sum) ! this is optional
5. sum := sum + input
6. input := ReadInteger()
7. Display("The sum is ", sum)

The translation from pseudocode is pretty straightforward... you already know how to Display(...) and ReadInteger().

One thing: you need to be careful about how you're printing out the count and sum. Try this...

System.out.println("(count, sum) = (" + count + ", " + sum+ ")");