I just receive errors when trying to build mobile

I am new in the development in Android and i am having some problems in my learning. I am trying to build my solution in my cellphone, he is a Android of version 6.0. I fetched for some tutorials in the internet and even here in the Stack Overflow and because of it a downloaded all the versions of android sdk, since the 5.0 until the 7.1.1 and even the extra packages. Even so i continue receiving the same errors when i try to build my solution. They follow below:

FAILURE: Build failed with an exception. Where: LuppApp Build file 'C:\Oxaguia spk\Trabalhos\Coach IT\Visual Studio\LuppICS\SolutionLupp\LuppApp\platforms\android\build.gradle' line: 289
What went wrong: LuppApp 1
A problem occurred evaluating root project 'android'. LuppApp 1
Keystore file does not exist: c:\lupp-Release.keystore LuppApp 1
Try: LuppApp 1
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. LuppApp 1
Error: cmd: Command failed with exit code 1 Error output: LuppApp 1
FAILURE: Build failed with an exception. LuppApp 1
Where: LuppApp 1
Build file 'C:\Oxaguia spk\Trabalhos\Coach IT\Visual Studio\LuppICS\SolutionLupp\LuppApp\platforms\android\build.gradle' line: 289 LuppApp 1
What went wrong: LuppApp 1
A problem occurred evaluating root project 'android'. LuppApp 1
Keystore file does not exist: c:\lupp-Release.keystore LuppApp 1
Try: LuppApp 1
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. LuppApp 1
Picked up _JAVA_OPTIONS: -Xmx512M LuppApp 1

I will be really grateful for everyone who can help me. Thank you.