Hi --
To create a form that submits to an Access (or SQL) database, you have to select that database when you first create the form (in the Based On section of the dialog box).
However, there are various reasons why, even if you did this, submit may be disabled for your form. This information will be present in the last window of the database connection wizard, when you set up your initial connection, or when you walk through it again, from the Tools / Data Connections window (select Modify, and you can walk through the connection steps again).
It is very easy to overlook this information. On the final screen, where you have the option of naming your data connection, there will be a checkbox you can use to enable submit. If that box is disabled, in the description of the data connection below, you'll find information on submit status, along with any reasons you aren't allowed to submit. The most common mistake is that the table you wish to build the form off of doesn't have primary keys set up on the table....
Hope that helps!