I know how to create a new numeric field but how can I fill it with numbers from 1 to what ever the highest number is?

use autonumber. This will automatically populate when a record is entered

I looked up Createtable and Type Property but I didn't see and Autonumber example. Can it be done on the fly using code?

What objective are you working towards?
The data in a a table is not stored in any particular order therefore to number records without imposing a sort on the table will lead to sporadic results.

If you are seeking to create a unique reference use an autonumber field, it won't always be incremental but it will give a bookmark to indicate record input, again you would need to consider how to sort the data.

An append query would probably be your best bet by importing all the records(via a sorted query) into a new table with an autonumber field.

Ian