Problem: List of recent posts not appear side by side

Hello,

I tried to make the recent posts appear side by side like the following picture (https://eches.net/trash/sidebyside.jpg). I’ve done the same as what the theme has but it only appears like the following (https://eches.net/trash/xsidebyside.jpg). I hope somebody can point me @ show me how to do that. I have no idea of what keywords need to google to find the solution. Thanks in advance.