For landscape work, I assume you're aware that you need at least one wide angle lens. I'd recommend the Tamron 17-35mm. It's not great for a full frame DSLR at short focal lengths, but it's fabulous for 1.6x cameras at every focal length and aperture. I have this lens and I can recommend it unhesitatingly. Test a few samples before you buy, however. I would also consider the Canon 50mm f2.5 compact macro. It's an absolutely world class lens, inexpensive, and very light.
With a kit like this you should be able to get fairly decent prints up to 16x20 and sell them at art and craft fairs, if you want. Galleries and stock houses are very tough, especially with 6 Mpixel files.
To post pictures here you have to upload to a website and then in the buttons above the window where you type your messages click on the one that says "Image" and paste the URL for your picture into the window that comes up. That's all there's to it, but you do need to be able to upload your pictures to a website.