I am very new in Linux. I only set up it. Which one is best for me for practicing basic application in Linux? I have set up Fedora 15.

Fedora, Ubuntu, Mint (based on Ubuntu) are all good. I have heard good things about Mint being very newbie-friendly.

I have heard good things about Mint being very newbie-friendly.

In command line I do not get any thing difference between Mint , Fedora and Redhat.
I may be wrong because I an a new learner.
Thanks.

I agree that Fedora, Ubuntu and Mint are all good for starters. Ubuntu is probably the distro most users are starting on these days, so there are a lot of websites where you can get help with it and find tutorials. Most of them actually apply to any linux distro, but there are some differences between the distros. One thing that is different is the package manager. Fedora uses yum, and Ubuntu uses apt. You will see very few differences on the command line.