Dtaa

I am having difficulty in understanding how DTAA works. Appreciate, someone thro light. I am INDIAN resident and INDIAN tax payer in current financial year. I have SALARY income in USA .I was living there since 4 years and in current financial year after working for 3 months I came back to India. My question is, I have paid tax on my 3 month salary for current year in USA , and rest month TDS is being deducted from salary in India. I want to know that I have to club my income to 3 month USA income to Indian income for payment of TAX or I can simply the tax on the rest of 9 month income only generated in India? Thanks