Uncaught (in promise): Error: StaticInjectorError(AppModule)[employeService -> Http]:

You need to import HTTPModule into your main module.

import { HttpModule } from '@angular/http';

@NgModule({
  declarations: [ ],
  imports: [
    ......
    HttpModule
  ]
....

Update

As per latest versions you should use HttpClientModule instead of HttpModule

Import like this

import { HttpClientModule } from '@angular/common/http';

@NgModule({
  declarations: [ ],
  imports: [
    ......
    HttpClientModule
  ]
....