Get the call in your mouth and say show. Elongate the SH sound "SHHHHOW" and you will get sound. Once you get sound try to blow one long note and keep the pitch steady.
For lower notes not very much tongue pressure on the reeds. For higher tones push your tongue up into the reed[toward the roof of your mouth]. Once you can geta low tone and high tone, try to make a middle tone[so you have 3 notes]. Then do a scale, low to middle to high then back down. When you can control that you are off and running. For some people this comes very easy, some struggle but don't give up. One thing for sure make sure you are trying to learn on a single reed or a double. I put a double in for most people when I get them started. There are other things you need to know to elk call but this will get you started.
Gselkhunter