diff --git a/CODE_OF_CONDUCT.md b/CODE_OF_CONDUCT.md
index 18c91471..690485d7 100644
--- a/CODE_OF_CONDUCT.md
+++ b/CODE_OF_CONDUCT.md
@@ -126,3 +126,5 @@ enforcement ladder](https://github.com/mozilla/diversity).
 For answers to common questions about this code of conduct, see the FAQ at
 https://www.contributor-covenant.org/faq. Translations are available at
 https://www.contributor-covenant.org/translations.
+
+by Mustafa
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index a086fa47..a0387035 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -1 +1,20 @@
-All contributions, bug reports, bug fixes, documentation improvements, enhancements, and ideas are welcome.
+Contribution guidelines
+Welcome Contributors!
+Thank you for considering contributing to the centralized repository. This document outlines the guidelines for contributing to the development of Shipping Rates and Calculations.
+
+Code style
+Please follow the coding style and conventions used in the existing codebase. This helps maintain consistency across the project.
+
+Documentation
+Ensure that your contributions are well-documented. Include comments in your code where necessary and provide a clear and concise description of your changes in the pull request.
+
+Testing
+Before submitting a pull request, make sure your changes have been tested thoroughly. Include relevant test cases and ensure that existing tests pass.
+
+Issue tracker
+Check the issue tracker for any open issues or feature requests. If you're working on something, please comment on the issue to let others know.
+
+Code review
+All contributions will go through a code review process. Be open to feedback and be willing to make changes if necessary. Code reviews help maintain code quality and consistency.
+
+Thank you for your contribution!
diff --git a/README.md b/README.md
index b1034661..b61147a2 100644
--- a/README.md
+++ b/README.md
@@ -9,7 +9,7 @@ Input:
    p, principal amount
    t, time period in years
    r, annual rate of interest
-Output
+Output:
    simple interest = p*t*r
 ```