ASP.NET表单显示表单字段基于另一个字段中的部分

I'm new to ASP.Net development, MVC 5, and pretty much anything Windows, so I'm sure I'm doing something wrong. I searched around for an answer here and found similar questions but I'm clearly doing something wrong...probably due the answers presuming more knowledge of the environment I'm working in...I'm new to ASP.Net development, MVC 5, and pret