Strengh Training??

Hello Everyone...I'm still fairly new here and have a question. I want to start adding strength training into my exercise and i'm not to sure how to do that. Right now me and the hubby are walking for our exercise. Is there a DVD that is just for strength training that could show me what to do? (I have many Jillian Michaels and Bob Harper DVD's but they are for the most part all cardio) We do belong to a gym but I cannot afford a personal trainer, and not really sure on how/what to do there besides cardio? Any help or advice would be great!