Hi Julie-Anne, going by the "Vermeulen" I presume that you are of South African extraction. On the South African Roots project homepage there are links to be found to sources. As Ronel says every denomination has different links and availability.
The only baptism record of a Jansen I could find was this one for Debora Maria Catharina, in the Dutch Reformed records. The names are similar but not the same. It might be a lead. :-)