quitting my job

So I've worked with this company for only 8 months. I'm the assistant manager. But in these 8 months my boss has been a complete jerk to me. So yesterday I got a wonderful offer from this other company & I have taken the job. So it's time to put in my 2 week notice. But my question for this is, would it be okay to just do a resignation letter? With my other job I just did a resignation letter & nothing was ever said. I need opinions & ideas on how to do this. I've always been a nervous person. I'm also the type of person who don't wanna hurt anyone's feelings or make anyone mad. Thanks ladies