Are you talking about starting Firefox, or having the browser open a wanted website?

On the startup page in a new Firefox tab you have shortcuts 1,2,3 or 4 rows what I'm asking is how do you personalize these? I have done one by opening a tab and just copying and pasting the URL & the URL for the Icon image but is there a more efficient way?

See:

• https://support.mozilla.org/en-US/kb/customize-new-tab-page
• https://support.mozilla.org/en-US/kb/hide-or-display-content-new-tab

Tiles you have pinned a website are stored in browser.newtabpage.pinned on the about:config page. The format is an array with {"key":"value"} pairs in JSON format: *{"url":"https://...","label":"label-name","customScreenshotURL":"url"} Unpinned items have a null value,so you can use that to skip tiles (start and in between).

• [null,null,{"url":"<url1>","label":"<label1>"},{"url":"<url2>","label":"<label2>"},null,{"url":"<url3>","label":"<label3>"}]

You can open the about:config page via the location/address bar. You can click the button to "Accept the Risk and Continue".

• https://support.mozilla.org/en-US/kb/about-config-editor-firefox

Cheers mate!