You can use Replace Field Contents in the Records menu to load a new blank field with serial number values.
Define a new ID field and use field options to set it up as an auto-entered serial number
Make a back up copy of your file
Use Show All Records to bring up all your records in the found set.
Click in the new ID field
Choose Replace field contents
Select the serial number option and also the "Update Serial Number in Entry Options" check box.
Then I will need to know how I get the computer to match the names from the master list to that of the class lists for relationship purposes
The above serial number is the field you should use in your relationships rather than names as two people could have the same name and people change their names when they get married or for other reasons and you don't want these issues to affect your records. Can you describe what you want here in a bit more detail?
Excellent! That worked just fine.
Now to answer the question of what happens next. I have another file that contains a persons name with class attendance information that doesn't contain their ID number. I need to know how I can add their current ID number to their name in the class attendance file so I can use the ID's in relationships to access both their personal information and class information.
If your current data doesn't have any people with duplicate names, temporarily define a relationship that links your records by the name fields.
As before, make a back copy first just in case you make a mistake.
Define a number field in this table, do not make it an auto-entered serial number field.
Use replace field contents to update this number field with a calculation that copies the serial numbers from the matching record in the table where you just set this up.
Now update your relationships to link the two tables by the serial number. Next, locate every place where you've put the name field(s) from this secondary table on a layout and replace them with name fields from the first table. Finally, delete the name fields from your secondary table as you will no longer need these fields.