Some Noob Questions

Ok, here is a pretty stupid question. I bought this new macbook pro and I am already facing some troubles. As soon as I got this I was doing some settings which enables me to see the storage devices on the desktop. But I don't remember to do it anymore? Please help.

Another one is I can't delete my files from my External Hard Disk from mac. But I can do it on windows. How do I enable it so that I can delete files on my External via Mac.

THANK YOU. Please reply soon.

Storage devices: Finder > Preferences > General > Show these items on the desktop.

External disk: Is it formatted as NTFS (right click > Get Info > Format)? If so, you won't be able to make changes since OS X has read only support by default. Your best bet is to reformat the drive as FAT32. Note though that doing this will erase its content.