With CSS properties, you can easily put two <div> side by side in HTML. Use the CSS property float to achieve this.
With that, add height:100px and set margin.
Example
You can try to run the following code to place two <div> side by side
<!DOCTYPE html> <html> <head> <title>HTML div</title> </head> <body> <div style="width: 100px; float:left; height:100px; background:gray; margin:10px"> First DIV </div> <div style="width: 100px; float:left; height:100px; background:yellow; margin:10px"> Second DIV </div> </body> </html>