It looks like a very basic question, still follow the below steps
Step 1: You need to create a github repository first
Step 2: Then copy the URL of the github repo
Step 4: Then add remote for the github repo (git remote add origin "copied repo URL")
Step 3: Then clone the repo (Readme files will cloned) (git clone "copied repo URL")
Step 5: Then add file (git add * or git add . or git add file name)
Step 6: git commit -m "your message"
Step 7: Then push it (git push origin "branch name")
Login to github and check your Repository