Change Theme Colour & Install extra buttons in frontend

Hi There

Can someone please help me, i don't know how to do any coding at all but are willing to learn how to do it.

What i would like to do is just change the default opencart theme colors to green, how do i do that and what code do i use where to do that? i want to change the storefront main website color to green, the buttons to a different green and also here and there other things?

Secondly i want to add a main page picture just like in shopify changing the main image or as example a facebook page on-top there is the common facebook page image, i want to add that in is that possible?

Lastly i also want to add a link on the storefront that goes to the admin section

Please help

I am using opencart 3.0.3.1
I have tried downloading green themes and some other extensions but realize that they are very limited to this version of opencart

Kind Regards
Richard

1) use browser to inspect the code
2)search the corresponding code and change it