WPF view dropdown list one below the other

I am just learning WPF in MVVM. In the view I want the drop down list to be beside each other. But its coming one below the other. Below is my code sinpet.

 <Window.Resources>
        <DataTemplate DataType="{x:Type vm:EmployeeListviewModel}">
            <vw:EmployeeListview/>
        </DataTemplate>
        <DataTemplate DataType="{x:Type vm:ProjectListViewModel}">
            <vw:ProjectListView/>
        </DataTemplate>
    </Window.Resources>

Regards

Raghu