Expecting that you use android studio...
Firstly check the build.gradle file of a previous app or just create a new one and check the build.gradle file.
Check the build.gradle file of the app which gives this issue. Just change it according to build.gradle in the running app.
Basically you'll have to change 2 main things here. Shown below:
compileSdkVersion = 23 // add the version which is in your running project buildToolsVersion = "23.0.2" /* add the version which is in your running project*/ minSdkVersion = 23 targetSdkVersion = 23 /*same as your build.gradle of running app*/
After the changes, clean and rebuild your project. It should work.
You could download the required sdk versions.