how to execute source code..

Answer 1

Add more in Description please, where you are about to execute it? here in SoloLearn or in your device.

In SoloLearn you simply just tap or click on "Run" button in Code Playground editor.

Otherwise, it depends on which tools you use ...

Answer 2

Run it through compiler and then run the program or run it through interpreter. Which to use depends on what tools support the language you use.