To be able to clone, commit and push changes to repositories on our git you ought to set up ssh keys. Generate new ssh key as
ssh-keygen -t rsa -b 4096 -C "your_email@example.com"
and add contents of a file ~/.ssh/id_rsa.pub as a new key to your account at https://gitlab.fel.cvut.cz/profile/keys .
cat ~/.ssh/id_rsa.pub