Complex sentence: Portstewart took another stride forward in 1979 when the applied to join the NW intermediate league, starting their campaign against Derry City before a few weeksk later opening a new pavillion at The Warren against RUC.
Split into simpler sentences: Portstewart took another stride forward in 1979, when they applied to join the NW Intermediate League. They started their campaign against Derry City and a few weeks later opened a new pavillion at The Warren, against RUC.