Often the answer to 'how to do this' is: break your problem into solvable steps.
You need to read your data from a file to a Matlab variable. Were you able to do that?
You need to find all unique IDs, loop over them and find all occurences of a given ID. Did you try unique, a for loop, and ismember?
You want to find the average and the standard deviation. Did you try a google search or guess a plausible name for functions that might calculate that?