Smart Phone can set the alarm time on basic Arduino?

I bought Arduino uno 2 weeks ago then have tried to make alarm time setting onto Arduino uno using RTC. The problems are when I send the setting of a time for alarm from android app. The text is changed to ASCII. What do I have to do? Do I need any other accessories? I try to make buzzing when the setting time is matched form android app to the RTC. I spend more than 20 hours now..
Please, help me!!!

Have a look at serial input basics for a simple reliable way to receive data.

Without seeing your code it is impossible even to guess at a solution.