Windows phone default having Ui like Metro type.There is no property to set corner radius for Windows phone buttons. But our requirement is to create a button with curve edges.so that we can do like this by overriding control template of button.
<Button HorizontalAlignment="Left" Margin="47,636,0,0" Name="SignUpButton"
VerticalAlignment="Top" FontSize="18" Background="#6BA92A" Click="SignUpButton_Click">
<Button.Template>
<ControlTemplate>
<Border BorderBrush="#6BA92A" Background="#6BA92A" CornerRadius="20,20,20,20" BorderThickness="2">
<Button Content="Sign up "
Background="{TemplateBinding Background}"
Height="65"
Width="348"
FontSize="{TemplateBinding FontSize}"
BorderBrush="#6BA92A">
</Button>
</Border>
</ControlTemplate>
</Button.Template>
</Button>