For ASP.NET 1,1, compile the code from the command-line,
and import/reference the resulting assembly.

Open a command window and make sure the
1.1 .Net Framework directory is in your system path, by running

PATH= %PATH% & C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727;

Substitute the correct drive letter if you're booting from a different drive.

Also, if you have a non-standard Windows install,
replace "windows" with your custom-named install directory.

To compile a single source code file, use :

csc /t:library /out:globallibrary.dll globallibrary.cs

To compile all .cs files in a directory to globallibrary.dll ,
use : csc /t:library /out:globallibrary.dll *.cs

If you need to reference a .Net Framework assembly or assemblies,
add them, separated by slashes :

csc /t:library /r:system.dll /r:system.data.dll /out:globallibrary.dll *.cs

Once you have compiled your assembly, place it in the /bin
directory of your application, and import your class Namespace in any aspx page:

<%@ Import Namespace="YourNameSpace" %>

If you're working with VS.NET, compile your assembly
as described and add a reference to it in your VS.NET project.

That will allow you to use Intellisense and get your
assembly's properties, methods, etc. when coding.

Juan T. Llibre, asp.net MVP
asp.net faq : http://asp.net.do/faq/
foros de asp.net, en español : http://asp.net.do/foros/
======================================
Oh, btw... this is .NET 1.1  ( I know, my work is nuts )