About running the code ....it is showing me error

throw err;
^

Error: Cannot find module ‘express’
Require stack:

  • c:\Users\HP\Downloads\WebNodeLive2017Winter-master\WebNodeLive2017Winter-master\Webinar12\express_server_rendering\server.js
    at Function.Module._resolveFilename (internal/modules/cjs/loader.js:976:15)
    at Function.Module._load (internal/modules/cjs/loader.js:859:27)
    at Module.require (internal/modules/cjs/loader.js:1036:19)
    at require (internal/modules/cjs/helpers.js:72:18)
    at Object. (c:\Users\HP\Downloads\WebNodeLive2017Winter-master\WebNodeLive2017Winter-master\Webinar12\express_server_rendering\server.js:1:17)
    at Module._compile (internal/modules/cjs/loader.js:1147:30)
    at Object.Module._extensions…js (internal/modules/cjs/loader.js:1167:10)
    at Module.load (internal/modules/cjs/loader.js:996:32)
    at Function.Module._load (internal/modules/cjs/loader.js:896:14)
    at Function.executeUserEntryPoint [as runMain] (internal/modules/run_main.js:71:12) {
    code: ‘MODULE_NOT_FOUND’,
    requireStack: [
    ‘c:\Users\HP\Downloads\WebNodeLive2017Winter-master\WebNodeLive2017Winter-master\Webinar12\express_server_rendering\server.js’
    ]
    }