Can't open pdfs on my Mac

Hello,

I received an email with some pdf attachments. When I click on the attachments for preview I get a message that states that the image should load momentarily. If it does not, I will need to update my adobe reader. I have updated my reader and I am still unable to open the pdfs. Could really use some help. I am not the most computer savvy individual so I will need a very dumbed down step by step tutorial to try and fix this.