Update CONTRIBUTING.md

Author: kaiiyer

CONTRIBUTING.md

@@ -1,4 +1,31 @@
-Fork the repo or clone the repo to the local system
+1. Fork the repo or clone the repo to the local system
 ```
 git clone https://github.com/kaiiyer/UBA.git
 ```
+
+On your computer, move the file you'd like to upload to GitHub into the local directory that was created when you cloned the repository.
+
+2. Open Terminal.
+
+3. Change the current working directory to your local repository.
+```
+cd <your dir>
+```
+
+4. Stage the file for commit to your local repository.
+```
+$ git add .
+# Adds the file to your local repository and stages it for commit. To unstage a file, use 'git reset HEAD YOUR-FILE'.
+```
+
+5. Commit the file that you've staged in your local repository.
+```
+$ git commit -m "Add existing file"
+# Commits the tracked changes and prepares them to be pushed to a remote repository. To remove this commit and modify the file, use 'git reset --soft HEAD~1' and commit and add the file again.
+```
+6. Push the changes in your local repository to GitHub.
+
+```
+$ git push origin your-branch
+# Pushes the changes in your local repository up to the remote repository you specified as the origin
+```