How to bootstrap a histogram of the frequency of truck weights.

Hi,

As part of my final year project I am studying the truck traffic load effect on road bridges. I have plotted a histogram of the weights of these trucks to give the frequencies of each weight of vehicle. These have been split into 1 tonne bins. I now want to bootstrap this histogram to randomly generate a frequency between 0 and ∑ fi which in turn will correspond to a weight. What function or coding should I be using for this as none of the literature I have found on bootstrapping seems to apply to this problem.

Thanks