Writing a cover letter and hit a snag...?

I'd leave out the "likely candidate for the position" line. Actually, to an employer eagerness to learn won't make you a likely candidate; experience will. I'd probably word it more like my eagerness to learn and work hard is an asset I could bring to the company. And tie in a line about why you'd like to have this position. Be honest, but do the best you possibly can with your cover letter. Sometimes if nothing stands out, the employer doesn't get beyond it. You can check online and find a lot of examples on how to write a cover letter when you have little experience to put on it.