Summarize this article:

Keep your arms straight and your palms face-up by your hips. Hold a barbell or dumbbells and slowly bend your elbow to start your curl. Bring the weight up to your shoulders and hold it for a count. Lower the weight back down until your arms are straight again to complete your rep. Practice doing around 10 reps for 2–3 sets. Choose a weight you’re comfortable with and doesn’t cause a lot of strain. As lifting that weight gets easier, you can use something heavier. Avoid swinging the weights up or down since you won’t work your biceps properly and you could injure yourself. As soon as you can finish your sets using 25 lb (11 kg) weights, attempt doing a pull-up. Stand in front of a workout bench with your feet shoulder-width apart and your knees slightly bent. Bend at the knees so you’re leaning over the bench and support your weight with one of your arms. Hold a dumbbell in your other hand and let your arm hang straight down. Slowly lift the weight up to your chest. Hold it there for a count before lowering it back to the starting position. Try doing about 3 sets that are 8–12 reps each.  Dumbbell rows help work out your back muscles and shoulders. Once you can comfortably row with 25 lb (11 kg) dumbbells, start trying to do pull-ups. Keep the rest of your body still while doing dumbbell rows, or you may work the wrong muscles. Lat pull-down machines simulate the motion you’ll use during a pull-up but you can choose the weight you're lifting. Slide the pin into a comfortable weight and reach up to grab the bar. Pull the bar on the machine down so it’s below your chin and hold it for 1 count. Raise the bar back up slowly to the starting position. Try doing 8–12 lat pull-downs per set for 1–2 sets.Increase the weight as you get more comfortable on the machine. Try to work all the way up to your bodyweight so you’re prepared to do your first pull-up.

Summary:
Practice dumbbell curls to work your upper arms. Work out your back and arms with dumbbell rows. Use a lat pull-down machine to strengthen your back.