Welcome to the forum and to Terragen. Alpine is indeed too uniform, but you can use masks (painted, simple shape, imported greyscale tif, etc) to mask areas that you want to use, and/or combine with a different noise, like a warped mix 1 or 2 (like the default terrain) by the inverted mask. Or merge two noises/shaders with 'highest raise' checked.
I attached a snow shader that I often use as a base. Inside the nodes you need to re-link the distance shader to the camera (every time you import this clip).
There is quite some documentation, but not all is covered extensively (and some people complain about it), but IMO a lot comes down to some experimentation and analysis of posted files. I don't know if you found
this page, but it has quite some tutorials listed.
Good luck, and hope to see some work from you soon.
