I would really appreciate it if someone can give me some tips on how to
relief pressure off my back leg (I think I'm doing something wrong
here). If you know of any good websites that give some pointers and
tips to beginner snowbarders I would be very grateful if you list them.

Also maybe get someone (friend or instructor) to check your stance,
angles and binding positions. Search the web for these and you'll find
some diagrams and info to do with your weight and board length. It
always amazes me how such subtle changes can make such big differences,
so for beginners this is even more relevant as you don't want to be
struggling against technique caused by a set-up issue. Setting up can
be a bind (no pun intended!) but it is satisfying when you start to
understand the physics in relation to your boarding and how different
muscles feel, and make successful tweaks..