(Photoblog theme) Help with coding

http://www.noiandiamo.com/7-tips-on-travelling-as-a-couple/

Hi everyone,
Need some expert help for a beginner here.
My website is above and I’ve managed to change some code via the inspect elements page to make it the way I like. However, I can’t figure out how to change in on my wordpress site.

I’m using Photoblog theme by tookoto.
I would like the column on the left to be smaller
.type-post .entry-meta, .type-page .entry-meta {
width: 90px;

and the entry content to be
padding-left: 0px;
font-size: 18px;

Can anyone help with the code on this?
Also I’m wondering if i can put it into my custom CSS or via the editor on my dashboard.

Any help would be muchly appreciated!!!