There are loads of suitable texts on analysing narratives from an ethnography. As well as the afore-mentioned Reissman book, Gubrium and Holstein's (2008) Analysing Narrative Reality is a good introduction. There is also the Handbook of Narrative Research edited by Jean Clandinin. The most useful for me in terms of putting things into context when analysing narratives from an ethnography was a book by Harry Wolcott called Transforming Qualitative Data. He breaks the data down into Description, Analysis and Interpretation. The work of Andrew C Sparkes, Brett Smith and Arthur Frank are all worth looking at depending upon your area of interest. Finally as a means of considering your own reflexive position within the ethnography, The Ethnographic Self (1999) by Amanda Coffey is fantastic.