Hello, I just wanted to ask how to find I1, hope somebody can help me

 

You need to show us your work. Because we do not solve homework for the users.
As a tip, you can take a look here:
https://en.wikipedia.org/wiki/Current_divider
https://www.allaboutcircuits.com/textbook/direct-current/chpt-6/current-divider-circuits/

 

What is the current flowing (and in what direction) in the bottom wire immediately below the current source?

If you have studied current dividers, that should be enough of a hint.

If not, then can you see how to combine the two left-hand resistors into a single effective resistance and use the answer to my earlier question to determine the voltage across both of them?