It truly depends on what type of muscle fitness you are looking for. My suggestion would be to start light and get your muscle used to lifting weight before you try and grow them. Using lifts that build your core muscles are the best lifts to start your regiment. Start by using some of the following lifts.
These can be done with just your body weight, or you can add a bar with weights accross your shoulder. Your feet should be shoulder width apart, you do just what it is called. Squat down until you are close to a 90 degree angle in your knee's.
These are done once again with our without weights. stand with your feet shoulder width apart. Step forward with one of your feet, keepint the other foot still. Make sure your step is a bit of a stretch. Pull your front foot back to its original position and repeat using the oposite foot.
This lift can be done using just a bar, a bar with weights, or dumbells. Using a bench lay flat and place your hands roughly shoulder width apart on the bar. Lift the bar off of its resting mounts. Bring the bar down till it touchs just below your pectoral muscle(just under the breast). Then push the bar back up. Repeat as many times as you feel you can safely do. Rest and repeat.
To do these you must find dumbells that you feel comfortable lifting a few times each. Lay face down on and inclined bench with the dumbels in your hands dangling below you. Pull the Dumbells towards your chest and let them back down slowly until your arms are fully extended again. Do as many as you feel comfortable with. Rest and Repeat.
These four lifts are called core lifts. They will work both the front of your legs, the back of your legs, your butt, your chest and your lats. I would suggest doing 8 repitions and at least for sets of each lift. Goodluck and I hope this helps.