Appium launching app with Ruby

I’m trying to open a pre-existing app with my actual android device with appium.

I’m very new to this so could any one help me setup the desired caps?
desired_caps = {
caps: {
platformName: ‘Android’,
platformVersion: ‘7.0’,
deviceName: ‘R38G8013SCD’,



@appium_driver =,true)
@selenium_driver = #appium_driver.start_driver
Appium.promote_appium_methods Object

I’m not even sure how to drive it properly…I got the selenium to open a browser and google but can’t figure out
how to open a application. and wandering how to set the appPackage and appActivity.

Any help would be really appreciated!! thx