I need help on Sims Medival on iphone?

I am really poor, and I need more money, so I wanted to buy fishhooks from the market so I can go fishing. I'm tired of stealing things, and it's just making more village sims dislike me. A lot of people have told me to go to the market and trade with the merchant. I went to the market and tried to trade with him, but he's not letting me. When you click on the merchant, five buttons pop up, and two of them are blue. I don't know which one to click so I can trade with him. The three yellow ones don't help me trade anything. How do I buy stuff from the merchant? Help!!!