Upload a document from a form into a SharePoint document library

The idea is that I have a form which I want to allow users to upload files into my SharePoint document library. I am just not just what to do after the 'HasFile' Statement. Some small snippets of my code below. I am just not sure how from the fileupload ID to get it into my document library. Please provide code.

<asp:FileUpload ID="FileUpload1" runat="server"/><asp:Button ID="Button1" runat="server"Text="Button" onclick="Button1_Click"/>

Server side code

protectedvoidButton1_Click(object sender,EventArgs e){if(FileUpload1.HasFile){//????}}