I clicked on a fake Whats App in an email today. Help please.

I stupidly clicked on a fake Whats App in an email today. It took me to a miracle weight loss cure site. How can I check if my Mac has been infected with a virus or malware? I have read so much conflicting information online about whether or not my Mac could be infected. My main concern is that I do a lot of internet banking and want to make sure that is safe. I am normally so careful with clicking on links in emails but today I just wasn't thinking. My Mac is OS X Lion Version 10.7.5.