Add additional floating small image over first background index image

Hi, I hope someone who understands Squarespace / CSS can help me.

I would like to add another small image to float below the Header text on the first page of my home index in Marquee. This would be an around 80px wide and 60px tall graphic logo of our partner organisation.

Is it possible to add another floating image element as well as the header and strap line? If so, would someone mind explaining how this is done? Thanks.

Best,

A.