This post is going to explain How you can customise A WordPress theme.
I should point out at this stage, that the explanation in this post and the demonstration video, are connected with this particular theme
Which is the Eleven40 Pro Theme from StudioPress
The generic of this explanation and demonstration, will apply to all themes, because all themes do have the same generics, specifically free themes
Some Premium Themes, quite obviously because they are premium, will differ in some respects, but they all come with instructions on how to use each customiser, so you can’t go wrong
The first thing you need to do is go to your customiser.
This you will find by clicking on appearance then customize