We'll begin with a very simple markup page, like the one shown in the following screenshot:
![](https://static.packt-cdn.com/products/9781788296540/graphics/assets/00c0d976-9eab-4b0a-963f-6fd7f2173315.png)
Figure 6.3.1: Our simple starting markup page for this lesson
What we have here is a TextBox control, then we have a Label control after the TextBox control--a very simple interface. We will collect a value, which will be the radius of a circle, then display some relevant information about the circle. Really easy stuff.
OK, go over to the Design view. What we currently have is shown in the following screenshot:
![](https://static.packt-cdn.com/products/9781788296540/graphics/assets/65cf6836-34a0-4ac8-98af-2da535d7fbcc.png)
Figure 6.3.2: Our starting interface in Design view
Again, we have a TextBox control and a Label control. Now left double-click on the box to bring up the event handling code. Do this next. Now it looks like the following screenshot:
![](https://static.packt-cdn.com/products/9781788296540/graphics/assets/79d302e0-754d-46e2-b4c6-fc654de8a14f.png)
Figure 6.3.3: Our starting Default.aspx.cs page