First let's define what is social theology and what is its purpose in the field of social science research.
Social theology is a concept that dates back to 1965. It is mainly a Catholic church-based concept because it was first published in what is known as the Modern World Constitution of the Church as dictated by the Vatican Council II, titled Gaudium et Spes.
The first tenet of the Gaudium is that all social injustice suffered by mankind is the church's business. The church places itself as the House of Mercy of the destitute and holds itself accountable for their well-being.
“the joys and hopes, the griefs and anguish of the people of our time, especially of those who are poor or afflicted in any way, are the joys and hopes, the griefs and anguish of the followers of Christ as well” (tenet 1, GS1)
Tenet 45 (GS45) states that the Church, as the ultimate salvation of the human soul is also responsible for saving the human body. It aims to suffer with those who suffer and walk side by side all mankind through the "pilgrimage" that is life. The final aim is to serve as the conduit between man and God after having experienced misfortune and social destitution.
Hence, the structure of your analysis should follow the same format of any other investigative research. However, when you site your foundations and the rationale of your research you have to base it on the tenets found in the Gaudium et Spes which places the Church as the axis of the existence of the poor and destitute.
In typical research papers your rationale and benchmarks will come from social scientists and psychologists. Not in a socio-theological paper. The difference here lies in the source of your primary document which is entirely religious-based.
This does NOT mean however that the analysis will lack validity simply because is theological. There is a respectable number of well-known social researchers who are either ordained ministers, priests, monks, deacons, or at the very least, deeply religious. They devote their lives to social research precisely because they want to see the influence of theology in society. Theology and history go hand in hand and there is plenty of information to get from studying how the Church has aided (or not) the socially unfortunate in different periods of history.
Therefore, familiarize yourself with the terminology of social theology, with the tenets of the Gaudium, and with the history of social injustice as it occurs in a specific place and time. Then, explore what role the church, or religious organizations, have played in the transformation of this social class, or how they have influenced any change in their situation.