Art as in artwork? Check Google.
If you're talking about the ART runtime, then you need to enable developer mode.
Goto settings->about phone->build number. Tap that box several times and you should see a message that you're now a developer.
Now hit back and you should see developer settings above about phone.
Tap developer settings, then tap the toggle button at the top right to turn the settings on. Scroll down until you see runtime. It'll say Dalvik. Tap that and you should be able to select ART. Once you confirm your setting, the phone will reboot.
Once it reboots, your phone will show a small box that says optimizing apps. Don't touch anything and let the phone finish its thing. Once it completes, all of the apps should be running using the ART runtime.
Sent from my XT1053 using xda premium