Images Fitting The Width Of Page

I am new to using wordpress and I know only very basic HTML and I can’t for the life of me work out how to fit my image the full width of the page, as it keeps resizing it.

I have an image on my front page; https://hollystringer.com/ and I wan’t it so that it fits across the the full width. This is the code I have inserted on the page at the moment

<a href="https://hollystringer.com/wp-content/uploads/2012/07/Front.jpg"><img class="alignnone size-full wp-image-151" title="Front" src="https://hollystringer.com/wp-content/uploads/2012/07/Front.jpg" alt="" width="3599" height="1708" /></a>

I would really appreciate some advice, I know this has been asked before but I don’t understand the HTML advice they’ve given. I have already tried changing the media settings, I have selected full size and not thumbnail.