Plz. Help Me

If you don't even know how to backup your iphone. You shouldn't be jailbreaking.

Take some time searching about jailbreak and read about it before attempting. It will just cause your headache when you have no clue to so many things.

 

1. You shouldn't jailbreak. Especially if you don't know how the iPhone backs up. By the looks of it you haven't synced your iPhone in 2 months, a sign of irresponsibility which can permanently brick your phone forever.
2. If you need help on jailbreaking, then you shouldn't jailbreak.
3. Please type in proper English.
4. If we pasted the program here then this post would be filled with a trillion 10101101001001011's.

Now that that's over with, here's the info you wanted.
*SYNCING YOUR IPHONE IS THE ONLY WAY TO BACK IT UP WITHOUT A JAILBREAK.
*Also, by syncing you will see that your OS is obsolete. Update your OS to 4.3.3 first before jailbreaking.
*Search "iPhone Dev Team" on Google. First result will send you to their blog. The newest post on their blog has the link to the tool called "Redsn0w". That's the one you need.
*After updating, search "iOS 4.3.3 ipsw" and download a 666MB file that has the name "iPhone3,1_4.3.3_8J2_Restore.ipsw". Run redsn0w after this download is finished.

*Please understand how Apple monitors your iPhone first before talking about irrelevant programs. TinyUmbrella DOES NOT BACKUP your iPhone; it saves Apple's signature of approval for restoring to a particular OS, so that when Apple stops approving restores for that specific version (e.g. iOS 4.0.1) you still have Apple's signature to restore with.
*All jailbreak tools are self-explanatory. 80% of people think if you jailbreak an iPhone, you automatically graduate from MIT as a computer science major summa cum laude. It's not that complicated; as long as you don't do anything stupid you'll be fine.
*TinyUmbrella should only be used if you want to return to a version of iOS after upgrading. Google how to use if you want; it's completely unnecessary to use it right now.

 

All of my starred points on my last post is all you need for jailbreaking.
Also, if what you mean by "install some applications to my iphone" is installing FREE apps, then you have completely missed the point of jailbreaking and should not do it.

 

It is against the rules to help people who want to steal apps. You're not getting help here.

 

You are very misguided and has a very clouded view of what jailbreaking is.

Just enjoy your stock phone dude.