Hii dear,
Syllabus of IFS exam is given below:

Paper I:

Current events of national and international importance.

History of India and Indian National Movement.

Indian and World Geography -Physical, Social, Economic Geography of India and the World.

Indian Polity and Governance -Constitution, Political System, Panchayati Raj, Public Policy, Rights Issues, etc

Economic and Social Development  Sustainable Development, Poverty, Inclusion, Demographics, Social Sector initiatives, etc.

General issues on Environmental Ecology, Bio-diversity and Climate Change  that do not require subject specialisation

General Science.

Paper II:

Comprehension

Interpersonal skills includingCommunication Skills

Logical reasoning and analytical ability

Decision-making and problem solving

General mental ability

Basic numeracy (numbers and their relations, orders of magnitude, etc.) (Class X level), Data interpretation (charts, graphs, tables, data sufficiency etc.  Class X level).

English Language Comprehension skills (Class X level)
For more details visit:
http://www.jeemain.info/indian-foreign-service-exam/
Good luck.

Hii

You need to give Union Public Service Commission (UPSC). The recruitment of candidates to Indian Administrative Service (IAS), Indian Foreign Service (IFS), Indian Police Service, Indian Revenue Service (IRS) is done through this exam only.

UPSC Civil Services Syllabus for Preliminary Exam-

 Paper I – General Studies-

• Current events of national and international importance

• History of India and Indian National Movement

• Indian and World Geography - Physical, Social, Economic Geography of India and the World

• Indian Polity and Governance - Constitution, Political System, Panchayati Raj, Public Policy Rights Issues, etc

• Economic and Social Development - Sustainable Development, Poverty, Inclusion, Demographics, Social Sector initiatives, etc

• General issues on Environmental Ecology, Bio-diversity and Climate Change - that do not require subject specialization

• General Science

• Paper II – General Studies

• Comprehension

• Interpersonal skills including communication skills

• Logical reasoning and analytical ability

• Decision-making and problem solving

• General mental ability

• Basic numeracy (numbers and their relations, orders of magnitude etc.) (Class X level), Data interpretation (charts, graphs, tables, data sufficiency etc. Class X level) .
  

All the best.

Syllabus for entrance exam for IFS which is UPSC is hsared below. 

https://university.careers360.com/articles/exam-indian-forest-services

https://competition.careers360.com/articles/upsc-civil-services-exam-pattern-syllabus