Image resolution quality query

Hi;

Sorry if this is posted in the worng place – feel free to point me in the right direction.

I’m completely new to this and am struggling with the quality of my images – specifically the featured image in my featured slider as you’ll see.

Please ignore the actual image currently there as it’s just a tester. I’m looking to find an actual photo with us both in for this.

Any suggestions on how to get this looking good too? Apart from taking the head shots off of course (haha)!

Ideally I’d like this image which will always span the top of the home page to be thinner and of course a much better, sharper image.

The website is http://www.cantravelwilltravel.com/

Thanks
Tanya