there's a 'Downloads' option at the top of the page. Click the 'Neopets Downloads' then you'd see a lists of programs with the price and quantity available for download. if you have enough points for a program, enter '1' quantity at the left hand side and click 'Buy Items' at the bottom of the page
If you havent already been warned then also dont double/triple post. some people do sleep and most of your answers are in the stickies located at the top. Anyway in short explanation - Everytime you post/make a topic you get a point. Once you earn enough points you may download whichever programs you require. (price is on the downloads section) Once you reach level 1 (125 posts) you may sell/buy items/pets/accounts but if you try BEFORE level 1 you shall be warned/banned?