Once you have your axes drawn, you need to assign each one a variable, and their graduations, so for instance you could make a graph detailing the temperatures on each day of the week. In this case, Monday to Sunday would go along the x-axis so there would be seven graduations (and therefore seven bars) and temperature would go up the y-axis. How high and how accurately the y-axis is depends on the scale. If the hottest day of the week was 28 degrees C while the coldest was 22 degrees, it would not make sense for the y-axis to go from 0 to 100 degrees. Therefore a suitable scale in this case would be from 20 to 30 degrees C.
After you have decided your scales, starting from the bottom on the x-axis, for Monday, draw a line (or bar) up to the temperature for that day. Do this for all days of the week and you should be able to see how the temperatures varied easily.
That's it, a bar graph!
There are some great explanations and visual examples of bar graphs at the following websites:
If you are having difficulty understanding bar graphs then it is certainly worth informing your teacher. Although you may be reluctant to out of embarrassment it is better to get help at the earliest stage than sit on the problem until it comes around to revising for exams. If you learn it correctly from day one then you will find it a lot easier to remember.