I want to learn how to code what Code should I start with

Answer 1

This highly depends on what you want to do with your knowledge.
If you want to do front-end design, it is best to start with html and continue with css and javascript.
If you want to be able to do "math-stuff", python should be your first choice.

I started with java, which is a very popular programming language. You can do a lot with java and it is very well documented in the internet.

Answer 2

If you are asking about which language you should start with, I would suggest python for it's simplicity and many application areas.
If you are asking about specific code, write code that does the one of the following:
1:Says "hello world"
2: Asks for user's name and greets them.
3: Finds the sum of two numbers.
4: Checks if a user entered an even number or odd
5: Checks if the user entered a whole number, fraction or just a words.

If you feel confident enough, you should do this:
A program that does 3-4 depending on the user's choice. (this will be useful to understand object oriented programming and functional programming as well.)

For extra challange, write program 2 as a function in a seperate file and include it in all the other programs.

Lastly don't do these on sololearn playground. Find another plaform to write and test the code. You can then include them in your sololearn codebase. Trust me. It is much simpler.