HTML/CSS Layout bootstrap HELP!

Hello, i create layout using HTML/CSS (attached) but looks a bit ugly for me.
Can you help me make it look better ? Thanks in advance.
Here’s my code HTML:

And CSS code :

It would be easier for people to help if you put the code up on Codepen. You can make a free account there and are able to share links to your code without people having to download it.

Thanks for the answer! I will try it.