If your other columns are bound, you could use the value of the combo box to determine the value to use in a .seek method against the primarykey of the table.
look up seek in help to find out the details.
The other option is to attach a query to the afterupdate event of the combo box using recordsets, and fill in the other (unbound) fields on the form by referencing the column names returned by the query...
for instance...
Dim db1 As Database, rst1 As Recordset, sql1 As String
Set db1 = CurrentDb
sql1 = "select * from your_table where table_column= '" & Me!Combobox & "';"
Set rst1 = db1.OpenRecordset(sql1)
rst1.Requery
If rst1.RecordCount <> 0 Then
Me!field1 = rst1!table_field1
Me!field2 = rst1!table_field2
end if
(the disadvantage of this is that the fields are unbound and you are getting a query result set as opposed to the first option where you would get an active dataset where you could move forward and backward using navigation buttons)