how to properly analyze?

After your game, chess.com will analyse your play.  What you do with it is up to you.  You can learn from your mistakes (the new analysis will even let you retry your errors); take the recommended lessons, or even do a self analysis by opening, middle, and end game.  It is much better than the previous editions.

I grabbed one of your games and started to analyse it. I normally play the game through myself (using an opening book or Game Explorer) to see where play deviated from standard lines. During this play through I look to see if I missed any moves and notice the consequence of moves. I start to annotate the game. Then I use an engine in two ways: (1) to see if I missed anything and (2) to play through lines if I don't understand something the engine is suggesting. 

However, when I looked at your game I noticed that you gave your queen away quite early. Then, later you missed the fact that your opponent could take your rook for free. To be honest, in order to improve you need to stop giving away material. One way to do this is to have a checklist before you make each move:

1. Can my opponent capture any of my pieces?

2. Can my opponent check me?

3. Can I capture any of my opponent's pieces?

4. Can I check my opponent?

The first two would have prevented you from losing your queen and rook in this game. The second two are for making sure you don't miss any easy opportunities. In my opinion, this is where you need to look in order to improve your game. Only once you have stopped giving away material cheaply are you ready to start analysing games. But it's just my opinion.

I show my analysis of your game below anyway in case it is useful. It seems that black played an almost perfect game by the way.

@corum  That was a very impressive and extremely nice of you!

Thanks guys - as it happens I do have some time on my hands so it was no problem