Hi @trouvaille
You do not have to register for leo threads separately since this is a part of hive only though you would need to login to via hive keychain.
Do you have hive keychain installed ?
I would be able to assist you one step at a time both with login (no need to register and you only need to login since you are already having a hive account.)
As per winning the $10000 prize that is the prize pool.
Can you win it? Yes you can.
How do I know ?
Because I am one the winners of the previous editions where the prize pool was much less.
Currently I am promoting Leo threads and assisting people in getting onto leo threads.
With this intent I have created a handy leo threads getting started guide which you can read here
Here is the link to join the $10000 quest
Are you are on discord ? I can take you and your friend one step at a time using discord
or some other social media like facebook
please share your discord handle

Coming to the part of the where you say the country you live in is very expensive I can relate to the situation as we are all facing this situation.
However threads can help you add a little more to what you make here on hive. In the current times every additional bit helps