Choose an area where you want to determine the status of population with the disease is to be determined, develop a questionnaire and take responses of the subjects served. Transfer the data to the computer SPSS Program and analyze.
The socio economic status of a population must be estimated by a questionary with proper items for evaluate scholarity, sex, etary group, economic income, dwellin status, services (electric light, potable water, etc.) and any else that can be important for the disease type. Then you must to categorize the responses and the statistic approach in first hand is descriptive (frequency tables and bar charts). Then if you want to compare this indicators with a non-disease population, you can use contingency tables, comparative bar charts, and if the sample is adecuate you can calculate association measures like Odds Ratio to know those variables that are associated with the disease as risk factors.
If you have multiple items that may estimate one's SES (e.g. education in years, portable water, housing, family members, etc.), you can run latent class analysis (google PROC LCA for SAS or packages in R). LCA is a subgroup analysis and can assist you to see the pattern of these items. I personally like this approach than a mere summation of items.
If you do not have multiple items, I would go with one's years of education.