Docker installed in centos7 failed after installation

[Root @ localhost Desktop] # rpm -qi docker
Name: docker
Version: 1.5
Release: 5.el6
Architecture: x86_64
Install Date: Sat 02 May 2015 12:12:36 PM CST
Group: User Interface / X
Size: 37603
License: GPL +
Signature: RSA / SHA256, Fri 02 Jul 2010 05:28:52 AM CST, Key ID 3b49df2a0608b895
Source RPM: docker-1.5-5.el6.src.rpm
Build Date: Fri 02 Jul 2010 02:32:06 AM CST
Build Host: x86-05.phx2.fedoraproject.org
Relocations: (not relocatable)
Packager: Fedora Project
Vendor: Fedora Project
URL: http://icculus.org/openbox/2/docker/
Summary: KDE and GNOME2 system tray replacement docking application
Description:
Docker is a docking application (WindowMaker dock app) which acts as a system
Tray for KDE and GNOME2. It can be used to replace the panel in either
Environment, allow you to have a system tray without running the KDE / GNOME
Panel or environment.

[Root @ localhost Desktop] # systemctl start docker.service
Failed to issue method call: Unit docker.service failed to load: No such file or directory.

Heads up! This alert needs your attention, but it's not super important.