Highly Customizable Template for a newbie

hi all,

i just switched from blogger to wordpress but am now clueless at customising my blog. https://www.theentrepreneurbusiness.com

i have played with a few themes but i cannot find one that i can easily customize to do the following:

-change to my own header pic
-add in adds on the side easily (like blogger)
-add in widget easily
-adsense ready
-SEO ready

can someone help direct me to free themes which are basic and can do the above?

my old blog is https://www.businessblog29.blogspot.com and i want to achieve similar style and functions.

thanks so much for your help!