All of the elements needed for human life can be found on Titan. But it would require a large amount of technology to make it work nothing that is beyond our current understanding or abilities in chemical technology, but a large amount of technology.
Solar power would not be very efficient so nuclear would be a good option to begin with, however much lower tech options are available. The lakes on Titan experience small tides of 1m per day which might be used for power generation and liquid hydrocarbon flow might be harnessed in some areas in an alien form of hydro power. Three more potential sources of power would be burning acetylene in hydrogen to produce ethylene (both available locally), wind turbines and hydrothermal power from deep wells.
Water is available in the crust of Titan in large quantities and nitrogen in the atmosphere. So electrolysis of water would be required to generate oxygen, a gas processing plant making use of the difference in boiling points of the different atmospheric gases could separate out nitrogen. Ammonia, methane and ethane are all present and a virtual organic soup of chemicals is to hand so should be possible to synthesise everything needed for human habitation.
That said I would not underestimate the sheer quantity of processes needed. All the raw materials are present but they would need a lot of processing to remove impurities and much more processing to transform them into all of the things humans would need. I would say 90% synthetic chemical plant and 10% habitat. It could probably become self-sufficient eventually, but this is not likely to ever occur for financial reasons and would not even be feasible for centuries due to the vast array of chemical and mechanical technology that would be needed.