Implement IDisposable and IEnumerable

[Suzie999]

I have a class which is using IEnumerable and I now need to implement IDisposable

class Class1 : IEnumerable<Class12>
{
    ;stuff
}

How can I do that?
My first thought was

class Class1 : IEnumerable<Class12> : IDisposable
{
        ;stuff
}

Which I obviously cannot do.

(edit)
Sorry, I believe it's

class Class1 : IEnumerable<Class12> , IDisposable
    {
            ;stuff
    }