How to add activity by global change

Dear All,

can anybody suggest a possible solution for the below query....

i wanted to add one acitivity(Job Description )which can be a WBS SUMMARY OR LEVEL OF EFFORT activity.

this activity has to be in the begning of all the Jobs( there are around 2000 no of jobs).

in this activity i have to attach the note book item and in that i will give information such as scope of work/material ect.

so i was thinking of using the global change  option to add this activty at once.

is it possible

thanks in advance