From fedora 22 , major change has take place. Fedora’s package manager yum is now replaced with dnf (which stands for Dandified yum.)
why dnf replaced yum ?
1) dnf has better dependency solver. dnf uses libsolv with hawkey as c and Python wrapper.
2) Yum API is not documented, while dnf is maintaining API documentation.
3) Yum only supports Python for extensions.
How to use dnf ?
see man dnf to check manual page of dnf on you fedora 22.
dnf install PACKAGE_NAME
dnf [options] <command> [<args>]
For more details you can read following articles .