angulr 2 services call c# web api

 my error:

 

OPTIONS http://localhost:57590/api/Employee/CreateEmployee 405 (Method Not Allowed)

e @ polyfills.js:3

t.scheduleTask @ polyfills.js:3

e.scheduleMacroTask @ polyfills.js:3

(anonymous) @ polyfills.js:3

send @ VM44:3

(anonymous) @ xhr_backend.js:117

Observable.subscribe @ Observable.js:56

Observable._subscribe @ Observable.js:114

MapOperator.call @ map.js:54

Observable.subscribe @ Observable.js:53

Employeeadd.register @ employeeadd.ts:28

View_Employeeadd0.handleEvent_20 @ /AppModule/Employeeadd/component.ngfactory.js:1148

(anonymous) @ view.js:408

schedulerFn @ async.js:94

SafeSubscriber.__tryOrUnsub @ Subscriber.js:223

SafeSubscriber.next @ Subscriber.js:172

Subscriber._next @ Subscriber.js:125

Subscriber.next @ Subscriber.js:89

Subject.next @ Subject.js:55

EventEmitter.emit @ async.js:74

NgForm.onSubmit @ ng_form.js:138

Wrapper_NgForm.handleEvent @ /FormsModule/NgForm/wrapper.ngfactory.js:31

View_Employeeadd0.handleEvent_20 @ /AppModule/Employeeadd/component.ngfactory.js:1146

(anonymous) @ view.js:408

(anonymous) @ dom_renderer.js:276

t.invokeTask @ polyfills.js:3

onInvokeTask @ ng_zone.js:227

t.invokeTask @ polyfills.js:3

e.runTask @ polyfills.js:3

invoke @ polyfills.js:3

localhost/:1 XMLHttpRequest cannot load http://localhost:57590/api/Employee/CreateEmployee. Response to preflight request doesn't pass access control check: No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'http://localhost:8100' is therefore not allowed access. The response had HTTP status code 405.