Yes... it will give you the ultimate orgasm! Another point to make here is that it good for the long term health of your prostate when you do it safely. Practice on yourself so that you know how, where and what way to satisfy your partner.
Where is it?
Before getting started there is a few necessary rules:
Don't do this massage if you have any discomfort in the anal area - get some medical advice if you are experiencing any discomfort.
Make sure your finger nails are well trimmed and filed as you don't want to scratch yourself as its painful.
Use a moist or lubed finger. (You can use a condom on your finger if you wish).
Do the following gently and slowly.
Now the how to achieve that G-spot orgasm...
Relax and start to massage the area around your ass for a few minutes and relax into the feeling of your finger stroking your ass. Gently insert your lubed finger into your ass, slowly massaging towards the perineum (towards your cock). As you massage you will feel a small shaped walnut gland... that's the prostate! Some guys don't have to insert their finger that far to reach it, others will have to go a couple of inches in to reach it.
Begin to massage one side of the prostate lightly for a few minutes, then move your finger slowly and lightly over to the other side. Alternate the massage to each side of the prostate for a few moments at a time.