Rocket Spanish Community

I am teaching ESL for the first time. I am using this course to help me communicate with my students. But also, i'm trying to use it to do my lesson plans except using it backwards: spanish to english.

Can anyone help me with suggestions in teaching the sounds that are not said in Spanish. We are really stuck on th and sh. besides sticking our tongues out and making funny sounds we are stuck.

Any other ESL suggestions would be great.
Oh, forgot to tell you, all my students are adults from Costa Rica. One speaks English well the others speak no English at all. I love doing this!