Rezing of image for wordpress slider and explanation

General information for the website: Health and fitness site
Description of requirements/features: I have an image which needs to be resized. Currently in its current form it is too zoomed in, when uploaded it should look the same as the image on the site at present. ( setbyset.com) .

I also need a step by step explanation on how this is done in a word document. with screenshots.

I will provide login details and image once agreed.

Please only sellers with good english as I need to explanation document to be very helpful.
Extra notes: I have an image which needs to be resized. Currently in its current form it is too zoomed in, when uploaded it should look the same as the image on the site at present. ( setbyset.com) .

I also need a step by step explanation on how this is done in a word document. with screenshots.