How can I print digital sheet music on my Macbook Air/IPad etc?

I'm struggling to find a website where I can download and print sheet music. Most need Sibelius scorch which is not supported on OS X 10.7 Lion. Any ideas? I do have Avid Scorch app on my iPad but can't seem to print from it.

It's mainly pop/rock music rather than classical. Websites such as musicnotes.com and musicroom.com use Sibelius.

Please help. This is driving me crazy!!! It should be easy and straightforward in this day and age!

Would appreciate any help- thanks.