you cannot write to multiple tables directly from fields in a single form unless you are lucky enough to be able to combine all the fields into a single UPDATABLE query and you use that query as the recordsource for your form... whether your query will be updatable depends on the detail of your data structure.
remaining choices are subforms (will most likely work) and recordsets (will certainly work).
the general route (in DAO) with recordsets goes something like this:
dim dabs as dao.database
dim rec1 as dao.recordset
dim rec2 as dao.recordset 'etc for as many recordsets as you like
set rec1 = dabs.openrecordset("nameOfTable1")
set rec2 = dabs.openrecordset("nameOfTable2") 'etc
'you can now use:
rec1.addnew ' or .edit
rec1!fieldName = forms!yourForm.TextBox.Value
'to add/edit stuff to the recordset (=to the table)
forms!yourform.textBox.Value = rec2!FieldName 'to set a text box from the table
'etc etc etc
you will find heaps of stuff in this forum on playing with recordsets.