A histogram shows how values are spread out: how many order lines are under $50, how many between $50 and $100, and so on.
First you need bins. Right-click a measure in the Data pane and choose Create > Bins.... Tableau suggests a bin size; you can type your own. It adds a new dimension, for example Sales (bin), whose values are the lower edge of each bin: 0, 50, 100.
Then build the chart: the bin field on Columns, and the measure on Rows as a Count. Count, not Sum: a histogram counts rows in each bin. Summing would show how much money each bin holds, which is a different question.
Show Me can do all of this in one click: put a single measure in the view and pick histogram.
To change the width later, right-click the bin field and choose Edit....