I have been going to gym for past 3 months.
How do I warm up my biceps? Please give me some suggestion. I dont know the rules.
What are the steps for improve my biceps?
Whether work out in low weight is improve our Musles?
In general, warming up your muscles only requires performing the movement with lower weights. It's fine to use sets of 5 and then taper off the closer you get to your work weight.
However, if you are having pain in your hand, I would check your form. Is that pain shooting up from the elbow? If so, it's possible that you are putting too much strain on that joint and have developed a bit of tendinitis.
Make sure you are exercising the muscles you think you are. For example, if you body is swaying just to get the bar up while doing barbell curls, you need to strengthen your core before you can improve your biceps--which in general is not a bad idea.
Since you're being kind of vague here, I can only give you a vague answer. If your biceps are not improving, then you are not providing them enough of a stimulus to produce an adaptive response (growth) from them. I can do almost all the bicep training I need with chin-ups or weighted chin-ups.
What are your goals? Health? Longevity? Performance?