Hover link

I want to change the colour of the hover-over links on my blog (www.schristian.eu). I want links to be different colours the mouse is over the link.

At the moment, links draw a black line when the mouse is over the link, but i want, red, yellow, blue etc.

Can anybody help?

Any ideas where i’d find this? I can provide code if you ask! ??

Thanks in advance!