How to open up documents

Hello folks,

I am new to this discussion board so please be gentle.... I dare say this questions has been asked many times before however I shall ask for my own benefit.

I have received documents, but when I try to open them it asks for a password to open the document. I was under the impression that my password was the same as the one used to to sign in but  this is obviously not the case. Can someone please help me to understand the correct process  before I go crazy...... Many thanks,  Michael