I have to make a spreadsheet for the first time.   I have been paid for
a project, and I have to keep a timesheet in minutes, which works best
for this project.  The time I’ve been paid for comes to 4,590 minutes.

I will have 4 columns: date in A, description of specific task in B, #
of minutes for that specific task in C, and current balance of minutes
used in  D.

So I start with 4590 in row 1 column D, and my first task entry is 45
minutes, which I enter in row 2 column C.

Question One: how do I set up C and D so that when I enter 45 in row 2
coumn C, row 2 column D will  automatically show a balance of 4545?

Question Two: how can I eliminate columns E and following, so that only
the four columns show?

thanks so much!