Hola Kathy

You can say "Dejad que os cuente..." or "Dejadme que os cuente", but the pronoun is placed after the imperative and stuck to it. 

We often omit the "me" in this use of "dejar" (let) because it is obvious. It is as if we were saying "Dejad que yo os cuente..." (Let/Permit that I tell you... = Let me tell you...)

I hope this clarified it.

Saludos

Inma