Learning anything new requires patience and practice. Read a few articles on the topic of ad writing or read some ads in magazines or newspapers. Think about who you want to target, what words would interest these people to click your ad? What words come to mind when thinking about SFI or TripleClicks? Write down some words or phrases that you think of and then go back and expand from them. Also, make sure to proof-read, there is nothing more irritating than bad grammar.