What camera will be good for beginners and why?

I'd like to have it from Nikon or Canon. Not too expensive.

Good for photos, of course, but for >concerts< too!

You want to be spoon fed and that is a disservice to you. What I would like to suggest is this:
1. Investigate the "concert" thing. How many friends are going to concerts and getting good results from their picture taking? I fear not many. BUT if you are determined on the concert thing you want a camera with the most zoom power you can get and still be allowed into the concert. My choice if limited to Canon or Nikon would be the Canon Powershot SX50 IS which sells for about $415.00 and in my opinion looks like a small DSLR, and That may get you barred from the concert.
So calming down a bit but still have a great camera, I would consider the Fuji Finepix S4200 $129.00 or the Fuji Finepix S4500 @ $150.00. The S4200 is discontinued but has been marked down to $129.00 to make room for it's replacement the S4500. Both Fuji's have long telephoto lenses (a lot of magnification for bringing long distances into view).

Are we talkin' dslr type camera-how much is not too expensive? Cheapest dslr about $460-
Nikon D3100
But, if you are only beginning photography, I don't recommend any dslr.
PS-Most people that ask which one Nikon or Canon usually mean a dslr.

>concerts<

That means, DSLR's are effectively ruled out
Unless you have a press pass, validated by the organisers of that particular concert

Bridge cameras appear similar to DSLR's, here the security people most likely bar it under the 'no professional camera' rule
Besides, they are pretty poor in poor light

Sony Cyber-shot DSC-RX100 Digital Camera
$648, http://www.bhphotovideo.com/...amera.html

Has a largish 1" sensor & a fast f/1.8 lens
Does a decent job at concerts

Once you remove that concert tag,
You can make do with something like the Powershot SX150 IS
$79.99, http://www.target.com/...A-13802261

Is it good for beginners, yes - it has the PASM dial / controls
so you have the basic controls
Is it good for concerts - no way. Good news is you can get it through security

Are DSLR's good for beginners
perfect!
any and any DSLR is just fine, with the 18-55mm kit lens
starts $450 & has auto mode too, till such time you are familiar with the controls

You can forget concerts - cameras that can do the job won't be allowed in, and cameras that are allowed in have sensors too small to cope with the light levels.

Work out a budget, talk to a dealer, and take your blinkers off. Canon and Nikon make good DSLRs (as good as the competition, they just shout louder), but for bridge- and compact cameras, you'll spend more money for less camera if you don't keep an open mind.

As long as you avoid Kodak, Benq, Vivitar and GE, you can't go far wrong.