Signed REST - Agent API

I've read this:

OAuth for Signed REST Communication
Getting Started: Using the Agent API (REST)

Now, can someone please explain me the oAuth parameters and where I should obtain the values:

oauth_signature=,

oauth_version= This one should be static (1.0),
oauth_nonce=,
oauth_consumer_key= This one should be the Application Key,
oauth_signature_method= This one should be static (HMAC-SHA1),
oauth_token=,
oauth_timestamp= This one should be generated

Basically I don't understand and I've been reading everywhere to find the answer but I don't find it. Where do I get the values for:

oauth_signature, oauth_nonce and oauth_token.

I have installed the application key into my account and all that jazz, and I'm using the values I found that correspond to what I have, but I get:

{"error":{"message":"Wrong credentials","time":"2015-11-10T16:54:27.000+02:00","internalCode":"26"}}

So I was thinking maybe I have oauth_signature, oauth_nonce and oauth_token wrong, since I've tried with the ones in the example and the first part of the Verification Code, but it doesn't work.

Thanks.