Typo3/cms install with composer issue


I am really new in learning about CMS.   I started to create a test projekt for learning about TYPO3 and creating extbase ext.

Now I am stucked in installing TYPO3 with composer it shows me this Problem.

couldnt find something in the web about this problem.

What do I have to do next? What do i have to looking for in the internet to solve the problem or could one of you explain me (if quick)