I have worked with several Mainframe DB2 databases. You need to do a couple of things.
1. Make sure that you have the correct DB2 ODBC driver installed on your PC.
2. Create a DSN to defint the datasource - ControlPanel/AdministrativeTools/DataSources(ODBC). Choose the system DSN tab and set up a new data source. The wizard should walk you through the process. You'll need to know the server name, the database name, a userid and password at a minimum.
3. Once the DSN is set up, open an Access database and go to File/Get External Data/Link - Choose ODBC as the file type - pick your new DSN - choose all the tables you want to link to.
4. Once you have linked to the DB2 tables, you can create queries with the query builder to select data from existing Jet tables and append the data to the DB2 tables. The DB2 tables MUST have unique indexes defined in order for you to update the tables via ODBC.