i am doing something wrong

so I have set the plugin up, but I am just in clear on how to get the images once the grid is set.

am I going to Posts then creating a post for every photo I want to use and then making sure I put it in my services category?? its driving me crazy

Or am I creating a Page and doing the above etc.

at the moment I have created a Post and the only time I can get the photo to be on my services page is if I use it as a featured image. but I then cant get text underneath the photo as a caption etc

please help!!!

I have 8 services to go so I need 8 photos I have searched and can not find a video on how to do this so I am sure its simple imjsut not getting it thank you