Is this your family in 1901:
http://www.census.nationalarchives.ie/pages/1901/Londonderry/Tobermore/Tobermore_Town/1531457/
If so, William’s occupation then was “Nailor” ie he made nails (which he probably did in a blacksmiths forge).
If it is that family then the relevant marriage appears to be between William Wisner and Jane McGlade. Their marriage was registered in Cookstown 7.1.1889. If you view the marriage certificate you should get the respective fathers’ names.
I looked for the births of their children and noted the following: William 29.4.1888; Alexander 23.2.1890; John 9.2.1892; Joseph 18.2.1894 & Matilda 26.2.1896.
You can view the original certificates on-line on the GRONI website, using the “search registrations” option:
https://geni.nidirect.gov.uk
You will need to open an account and buy some credits. It costs £2 (sterling) to a view a certificate.
Statutory birth registration started in Ireland in 1864 so you may be able to locate both William and Jane’s births on the site too. However for their parents you will need to rely on church records, which means you would need to know where they were living when they were born. Some church records are on-line on the rootsireland and fmp sites but not all are, especially many Presbyterian records. You might need to go to PRONI (the public record office) in Belfast to search them.
If the above is not your family, perhaps you can post a link to them in the 1901/1911 censuses so as I can trace the correct one.