Image size and alignment

On my homepage I have created images I am using as links to my featured blog posts that I would like to align in a 3 column, 2 row fashion. I would also like the images to be the same size as my Instagram photos below, however, when I adjust the size, they bump down to the next row. Also when I align the images and then view the page from different computers/browsers the images will move and display in a different alignment on each page.

I have read the documentation for this theme and even searched on google/youtube and have not been able to solve this issue.

How can I adjust the size and alignment of the images?

My website is: ashleyhilton.net

To create the featured posts on my homepage:
First I created a jpg image and uploaded it to wordpress
Next I inserted the 6 photos into my homepage and adjusted the size so they would fit 3 across 2 down.
I published the page and noticed that they move around when opened on different computers/web browsers. Also I would like to make the size larger (like the photos in the instagram feed below) however they bump down to the next row.

Let me know if you need any more information.

Hello @ashleyhilton13,

I have just checked your home page and it looks like this issue requires some coding and testing on different screen resolutions, this goes beyond our support policy. It’s considered advanced customization. As an option, you can find a reputable freelancer on Upwork for this kind of service.

Kind Regards, Roman.