Macro to automatically add text and date in excel column.

Hi all,

I am a newbie in macro programming and i really want to learn this. I have a file here which needed a macro.

I have done the column A = which automatically add the word "CSA" to the input number.
In column B = ID
Column G = a dropdown list consisting of Post Validation and Loading only
Column I = Is the date of completion (eg. i finished the task today the date should be 8/6/2014 plus the time)
Column J = Remarks (Should be DONE or if they have another remarks)

What i want to do is when i update column A, column B, I and J should be updated.

for other columns no worries i can have it updated manually.

Any help would be much appreciated. And also if you have much better approach please feel free.