Once you have paid for the painting, and it is delivered to your house or business, you are the owner. I retain the copyright, so you may not make reproductions for sale without my permission. However, you are certainly free to sell the original art again to someone else.
If you wish to sell your painting, there are many avenues:
The first option (and I hope the one that you will use), is to contact me. You will have to ship the painting to me, and then I will list it for sale on my internet gallery. You will set the selling price. I charge a commission fee equal to ten percent of the sales price.
The advantage of this arrangement is that I am the artist and I
promote all my work all the time. People who like my work look at my galaxy
from time to time, to see what is new and what is available. I have a vested
interest in getting the best price for you! I would also like you to have a great
experience and buy from me again in the future.
A second option is to contact one or more art gallery and see if they would like to sell the painting for you. If a gallery sells it for you, their fees are typically 40% of the sales price or even more.
A third option is to sell it personally. If someone you know likes the painting, and wants to buy it for a good price, you can definitely sell it to them too.