Erro na Instalação do Express no NodeJs | Node.js: Inovando com Javascript no backend

Estou tentando instalar o Express no NodeJS Versão do NodeJS 4.5

Msg

npm install express -save
npm WARN package.json casadocodigo@1.0.0 No repository field.
npm WARN package.json casadocodigo@1.0.0 No README data
express@4.16.3 node_modules\express

Pasta de C:\temp\Alura\nodeJS\aula1\CasaDoCodigo\node_modules\express

21/09/2018 10:37

. 21/09/2018 10:37 .. 21/09/2018 10:37 0 express.txt 21/09/2018 10:23 107.294 History.md 21/09/2018 10:23 224 index.js 21/09/2018 10:23 lib 21/09/2018 10:23 1.249 LICENSE 21/09/2018 10:23 4.434 package.json 21/09/2018 10:23 4.777 Readme.md 6 arquivo(s) 117.978 bytes 3 pasta(s) 19.809.271.808 bytes dispon¡veis

Depois tento rodar o projeto abaixo (como ADM ) e estou recebendo a msg,

C:\temp\Alura\nodeJS\aula1\CasaDoCodigo>node app.js events.js:141 throw er; // Unhandled 'error' event ^

Error: listen EADDRINUSE :::3000 at Object.exports.errnoException (util.js:907:11) at exports.exceptionWithHostPort (util.js:930:20) at Server.listen2 (net.js:1250:14) at listen (net.js:1286:10) at Server.listen (net.js:1382:5) at EventEmitter.listen (C:\temp\Alura\nodeJS\aula1\CasaDoCodigo\nodemodules\express\lib\application.js:618:24) at Object. (C:\temp\Alura\nodeJS\aula1\CasaDoCodigo\app.js:6:5) at Module.compile (module.js:409:26) at Object.Module.extensions..js (module.js:416:10) at Module.load (module.js:343:32)

o que pode ser?