Passing data to a web from from a aspx.cs file in ASP.NET

I have this开发者_如何学Python input in my web form:

 <input type="text" id="keywordSearch" value="Keyword" runat="server" />

How do I get this data into there (it's from my Page_Load):

 string keywords = "This is my keywords!";

Thanks!

Missed the part about it being a regular HTML control:

keywordSearch.Value = keywords;