To start Farming (Members Only skill) you will need to find a Farming patch. There are different types of patches around the world where you can grow different things. When you arrive at a patch for the first time it will be overgrown with weeds. You will need to clear these weeds with a rake. You'll then want to treat the soil with compost (bought from the farmer, a farming shop, or you can make your own). In most cases, you'll then use a seed on the farming patch, while having a seed dibber in your inventory, to plant it. Use a watering can on the new plant so it will start growing (not needed if you pay a nearby farmer to take care of your plants). Take care to note that your plants can get diseased and die if left alone.
A way to start making some gold pieces is by levelling up a skill such as Woodcutting, Fishing, or Mining. These three skills (Woodcutting, Fishing, and Mining) are known as the 'Big Three', and they have been the three primary money-making skills commonly used by players to make money in RuneScape. Or you can just go to SSEgold to see if they got your solution.