Carol,
The marriage between William & Jane Trimble appears to have been registered in Lisnaskea 1857, Volume 7, page 177. (His surname is indexed as Brownfield). That cert should give you their parents names, addresses etc.
You can order a photocopy from GRO Roscommon for ?4 per certificate. Put the place, year, volume & page number on the application form (anywhere). Don?t worry about leaving some boxes blank. You don?t need to fill them all in if you have the reference details. http://www.groireland.ie/ You have to post or fax the form to them but they will e-mail the copy certificate to you if you wish. Tick the relevant box on the form.
Tradition was to marry in the bride?s church (assuming the couple attended different churches) so that may be the place to look for the bride?s baptism and that of any siblings. Unless it was a registry office marriage, the specific church and denomination will be on the certificate. (Probably Church of Ireland and in the parish of Aghalurcher).
Statutory birth registration only started in Ireland in 1864 so you won?t find a birth certificate for William born 1854, nor for his parents. You might find his baptism but the records are unlikely to be on-line. You may need to look them up in PRONI (the public record office) in Belfast. You would need to know his denomination and where he was baptised. The groom?s address on the marriage certificate should be a clue as to where the couple may have settled, and so you can work out which church they attended from that. You may also be able to find him in the Valuation records, once you have the townland name.
If the parents died before 1864, again you won?t find a death certificate for them. There?s a Jane Bloomfield death registered in Lisnaskea in Oct ? Dec 1894 est year of birth 1812. Seems a bit old for someone who married in 1847, but it?s possible.
Griffiths Valuation for 1862 lists several Trimbles farming in Carrickpolin (note spelling). 2 Johns and William.
The 1901 census indicates they were all Church of Ireland, so those would be the records to search if you want to research them. By 1901 there?s just the one family in the townland:
http://www.census.nationalarchives.ie/pages/1901/Fermanagh/Grogey/Carri…
Elwyn