I am convinced that I need to incorporate weight training into my exercise routine. I have a membership at my gym at work. I go 4-5 times a week, first thing in the morning.

I walk and do yoga on weekends/holidays. I want to spend my gym time lifting weights. I also have limited gym time -- 20-30 minutes, max.

I already know that a gazillion reps of those light dumbells is pretty useless. My gym has dumbells, free weights and weight machines. I only know how to use about half of the machines and I only know a few dumbell routines.

Can anyone advise me on what makes most sense to spend my time doing? I do upper body twice a week and lower body twice a week, and I know I am woefully ignoring my core. I've been doing the heaviest weight I can lift, and still manage three sets of 8-10 reps at that weight.

I have no idea how to do a squat or a deadlift and I don't have any kind of spotter or support. The men downstairs lift, but the women all stick to the treadmills and elliptical.

In my month so far, I can already see definition in my arms and collar bones, and I feel good. But I really have no idea what I am doing.

Any advice, or a website with pictures of step by steps?