Hi josette33
If you're familiar with changing in K2.css file, you can simply copy the k2.css file from K2 component:
/components/com_k2/css/k2.css
To template folder: /templates/t4_blank/css/ (I suppose you're using T4 Blank template and there is no k2.css file at this moment)
and make change as you wish.
And, of course, you can also customize style for K2 component via the custom css of T4 template.
Regards