When you check the repository, you may not see some files. So, my suggestion is to download the repository to avoid the problem.
Note: If you know and can code in C++ or, Java language; then you can start from "Beginner Level 02.txt" and after that "Beginner Level 03.txt" file.
First if you are completely beginner in programming, check the "Beginner Level 01.txt" file. After that, check the "Beginner Level 02.txt" file. Then, "Beginner Level 03.txt". You will get some problem or question links in these .txt files which are mentioned earlier. After completing the 3 steps, read and follow the instructions of "Competitive_Programming_Guide.pdf".
https://docs.google.com/spreadsheets/d/1C7j2CbguEN5cVEwsJQ6ZK9Yf8XUXOntP66mWA2n7Qh4/edit#gid=0
- https://www.codeforces.com
- https://www.codechef.com
- https://www.atcoder.jp
- https://www.leetcode.com
- https://www.lightoj.com
- https://www.spoj.com
- https://www.hackerearth.com
*Note: If you are unable to code at the beginning level of a problem, see others' code. So, google it. But please first try your best
If you know how to code, then you must know how to calculate the time complexity of a code. So, check the "Big O Notation.txt" file. Whenever you code for a problem, you have to calculate the time complexity. It is one of the best ways to practice it.
It is the calculation of memory usage of code.
You can check and read the "Math.pdf" file. Here, you can learn some math tricks.
-------In Sha Allah-------