There’s marriage registered in Glenties 1874 Vol 2, page 140. On that page are Michael Carr & Margaret Manelis. Suspect that may be your couple. Rootsireland may have a transcript of the marriage on-line or you can order a copy of the original from GRO Roscommon. You can order a photocopy of the civil certificate from GRO Roscommon for €4 (euros). http://www.welfare.ie/en/Pages/Apply-for-Certificates.aspx
You have to download and print off the form. Then either post or fax it back to them. You can’t e-mail your order to them. However if you want them to e-mail the cert to back to you, they will do that, so tick the relevant box.