I have some PDF's issued from CSE you can refer them for free
Introduction
https://cdn.cse.lk/pdf/investor-portal/intro-to-cse-sinhala.pdf
How to read and understand Financial Statements from companies
https://cdn.cse.lk/pdf/investor-portal/Understanding-Financial-Statements-Sinhala.pdf
Stock selection guide
https://cdn.cse.lk/pdf/investor-portal/Stock-Selection-Desision-Making-Sinhala.pdf
Introduction
https://cdn.cse.lk/pdf/investor-portal/intro-to-cse-sinhala.pdf
How to read and understand Financial Statements from companies
https://cdn.cse.lk/pdf/investor-portal/Understanding-Financial-Statements-Sinhala.pdf
Stock selection guide
https://cdn.cse.lk/pdf/investor-portal/Stock-Selection-Desision-Making-Sinhala.pdf