can anyone please tell me how to create LOV manually in apps?

Create a lookup for lov values with type, code and description.
Now comes the UI- whether you want to create LOV in forms, JSP based applications or in OA framework. Each has different type of implementation.

What application are you working on?

Go to system administrator responsibility & then go to Applications->validation->set here define the LOV & in Applications->validation->values you can set the values for that LOV.