displaying photo on homepage main article

https://codex.www.ads-software.com/Using_Images#Inserting_Images_into_Posts describes the basic process but you can skip the ‘upload’ part as the photo you want is already on your server.

Use the Gallery tab within the Media Uploader to locate the photo you want and then follow the instructions as above.

cheers, then how do I make that display on homepage?

Edit your Home page and then follow the instruction within the link above.