If you do not have the Drawing toolbar displayed in Excel, add the toolbar and then look at the AutoShapes tool. It has flowcharting symbols for drawing a flowchart. Once you have started a flowchart with the Flowchart options under AutoShapes, you can change an "AutoShape" by clicking on Draw, Change AutoShape, Flowchart.
To display the Drawing toolbar, right click on a blank part of the toolbar at the top of Excel and select, i.e. click on, Drawing from the list of toolbars.
Try searching Help in your Excel on key words, draw flowchart, or something similar. Excel 2003 has Help info on this. I also have Excel 97 on an older computer. It has the flowchart drawing tools, but I found nothing in it's Help on drawing a flowchart.