Lost

I was using microsoft office for windows and saved my documents on a USB storage device.Now I went and bought myself a macbook pro which has excel.When I use the USB and open my documents I'm only able to read the files,I can't edit any of the documents.Does anyone have suggestions for me.I'm really lost as to what to do.

OS X cannot write to Windows NTFS formatted drives

You have 2 choices to enable NTFS full support on the Mac

Parragon NTFS (better support - costs $20
Paragon NTFS for Mac OS X software

MacFuse (open source and free)
macfuse - The Easiest and Fastest Way to Create File Systems for Mac OS X - Google Project Hosting