I'm all new to ASP.NET so I'm going to need lots of help

. I'm trying to create a Guestbook and I've put the guestbook1.aspx and guestbook1.xml into C:\Inetpub\wwwroot\daniel\. When I'm trying to run the guestbook.aspx all works fine until I hit submit and I get this message:

Access to the path "c:\inetpub\wwwroot\daniel\guestbook1.xml" is denied.
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.
Exception Details: System.UnauthorizedAccessException: Access to the path "c:\inetpub\wwwroot\daniel\guestbook1.xml" is denied.
ASP.NET is not authorized to access the requested resource. Consider granting access rights to the resource to the ASP.NET request identity. ASP.NET has a base process identity (typically {MACHINE}\ASPNET on IIS 5 or Network Service on IIS 6) that is used if the application is not impersonating. If the application is impersonating via <identity impersonate="true"/>, the identity will be the anonymous user (typically IUSR_MACHINENAME) or the authenticated request user.
To grant ASP.NET write access to a file, right-click the file in Explorer, choose "Properties" and select the Security tab. Click "Add" to add the appropriate user or group. Highlight the ASP.NET account, and check the boxes for the desired access.
Source Error:
Line 38: // Insert the new element into the XML tree and save
Line 39: myXmlDocument.DocumentElement.InsertBefore(myXmlEl ement, myXmlNode);
Line 40: myXmlDocument.Save(Server.MapPath("guestbook1.xml" ));
Line 41:
Line 42: // Re-bind data since the data has changed.
Source File: c:\inetpub\wwwroot\daniel\guestbook1.aspx Line: 40
Stack Trace:
[UnauthorizedAccessException: Access to the path "c:\inetpub\wwwroot\daniel\guestbook1.xml" is denied.]
System.IO.__Error.WinIOError(Int32 errorCode, String str) +393
System.IO.FileStream..ctor(String path, FileMode mode, FileAccess access, FileShare share, Int32 bufferSize, Boolean useAsync, String msgPath, Boolean bFromProxy) +888
System.IO.FileStream..ctor(String path, FileMode mode, FileAccess access, FileShare share) +45
System.Xml.XmlDocument.Save(String filename) +91
ASP.guestbook1_aspx.GuestbookPost_Click(Object sender, EventArgs e) in c:\inetpub\wwwroot\daniel\guestbook1.aspx:40
System.Web.UI.WebControls.Button.OnClick(EventArgs e) +108
System.Web.UI.WebControls.Button.System.Web.UI.IPo stBackEventHandler.RaisePostBackEvent(String eventArgument) +57
System.Web.UI.Page.RaisePostBackEvent(IPostBackEve ntHandler sourceControl, String eventArgument) +18
System.Web.UI.Page.RaisePostBackEvent(NameValueCol lection postData) +33
System.Web.UI.Page.ProcessRequestMain() +1277"
The problem is I don't know how to grant access rights to the file, because I think I've tried most things in ISS and I don't even have a security tab if I right click the file in explorer. Is there anything else than brains I migt have missed during installation perhaps? I have frameworks SDK and SQL server 2000 installed. Help plz!