Select the students you want to update the emails of from the Start Page by choosing a filter, then using the Group Functions Dropdown and choosing Quick Export
It should bring you to Start > System Administrator > Page and Data Management > Quick Export
For the fields, you want Student_number and Student_Web_ID (so you know which number goes with what student) and then whatever field you want to edit. In this example, we will do locker numbers.
Make sure the delimiter is set to Tab and Column titles on 1st row is checked
Click submit
From there, you'll get a text file with the information, open it up in Excel. It should look something like this (except without the blue bars, obviously)
In Column C, fill in the locker number for each student
In Column D, fill in the combination for that locker
Then, in the top left, click Importing and Exporting, then Quick Import
Select the students table and your file. Make sure suggest field map is checked
Click import, which should take you to a page to verify the fields look right. Also make sure to check to exclude the first row and to update the records.