How to populate the datagrid depending on combobox selection?

I am very new to wpf and mvvm both... I went through lot of articles saying I should use selected item property can be used, I tried it's not working... when I change my selection it reflects in combobox but the datagrid not populating, so my question is how do I do that ?

i am using entity framework
I have interface igetdatarepository which has below task
Task<List<employee>> getasyncamployee();

Task<List<employee>> getasyncemployeewith(into salary)


Then I have a class which implement this inter face
Getdata

Private dbcontext _context = new dncontext();

Public async Task<List<employee>> getasyncamployee()
{

Return await _contex.employee.tolistasync();
}

Public async Task<List<employee>> getasyncamployee(into salary)
{
Return await_context.employee.Include(e => e.Salary == salary).tolistasync;

Now the view
<combobox itemsource="{binding salarylist}" Selectedvaluepath=value selectedvalue ="{binding employeedata, mode=two way}


And viewmodel


Igetdatarepository _getdatarepo;
Public EmployeeViewModel(igetdatareposotory repo)
{
If(designerproperties.getisdesignmode(new System.Window.dependencyobject())) return;

_Getdatarepo = repo;
}

Private employee _employeedata;
Public employee employeedata
{
Get
{ return _employeedata; }
Set
{
SetProperty(ref _employeedata, value);
}
}


And I am using c#