Design time
You can access and modify the style for different elements in RadCommandBar by selecting the element and customizing its look by the Properties section in Visual Studio
Figure 1: Customizing CommandBarStripElement's border at design time.
Programmatically
You can customize the elements at run time as well:
Figure 2: Customize elements
Customize elements at run time
this.radCommandBar1.Rows[0].BackColor = Color.Lime;
this.radCommandBar1.Rows[0].DrawFill = true;
this.radCommandBar1.Rows[0].GradientStyle = Telerik.WinControls.GradientStyles.Solid;
this.radCommandBar1.Rows[0].Strips[0].BackColor = Color.Yellow;
this.radCommandBar1.Rows[0].Strips[0].BorderColor = Color.Red;
Me.RadCommandBar1.Rows(0).BackColor = Color.Lime
Me.RadCommandBar1.Rows(0).DrawFill = True
Me.RadCommandBar1.Rows(0).GradientStyle = Telerik.WinControls.GradientStyles.Solid
Me.RadCommandBar1.Rows(0).Strips(0).BackColor = Color.Yellow
Me.RadCommandBar1.Rows(0).Strips(0).BorderColor = Color.Red