Notice the change in pronunciation of the “t” in “let”, because of the following /m/ sound, which is made with your lips. Use your lips for the “t” too, then bring in your voice and let the air out of your nose for the /m/ sound. Don’t open your mouth between the sounds. Keep the front of your tongue touching your top teeth for the two /ð/ sounds also, so they become one long sound. The spaces I have between words are to make it easier to read. We don’t have spaces between the words in a phrase when we speak.
You might say this to a guest when they arrive, to offer help with a coat or bag.