Make changes to wordpress site

I installed a themeforest wordpress template and would like to someone to make changes to it for me.

Example:
change color scheme
change css stylesheets
add/remove background images
add/remove page content
add/configure many plugins

I need an EXPERT in wordpress as I want to be sure the changes do not effect, slow down, or break my website. I’m looking for someone who understands wordpress programming and can help me make more complex modifications.