how would i go about gitting the rigths to a popular band/song such as the beatles?

To get the rights to the songs?  Are you planning to just use it or buy the rights outright?

I would first contact the record company that put the song out.  They could put you in contact with the band's manager or whoever handles that kind of stuff.  Then you can try to hammer out some sort of an agreement.  But to help you further, I'll need more details, like what exactly do you plan to do?  How are you going to use songs you seek?  Stuff like that.

From past experience (with law degree and with my father formerly working for a music company) to buy the rights of the song outright, for a beatles song, would cost you millions and millions.

if you are talking about using the song during a screenplay or script, it is usually an accredited production company that will contact the record company to discuss the use of the songs in the film. if the production company is small, or the project (for the record compnay owning the rights will want to know what the project is) the record company may want to see the scene in which the song will be used, or indeed if it is to be the theme tune, read a few of the spec scripts.

as for people like us buying the rights to songs. Nope. not usually. independent cinema usually get them for free. donated and the rc get a slice of profits.

Yes, what you buy is a license to use it for a specific purpose.  You need both the publishers permision if you are only using the song, and the records company's permision if you are using the recording.

Just remember that you aren't wanting to buy the rights to the song (big songs are worth mega bucks) just a license to produce x number of copies in a specific format.

That is much less bucks. 

I've written and produced title songs for indie productions and never made any money other than what I gave myself out of production costs. 

I'm making a short film with a group of friends I know. We made our first film last year, through our school and it was successful in many competitions. We want to use Michael Jackson's "Earth Song", at the end of the film. How do I go about this?

Good luck . . . I once tried to get rights to use a 1980s pop song ("Hey Mickey") in my film, and the singer--I forget her name--wanted $35,000.  Michael Jackson will be more expensive.

I've heard that you can get "non-profit festival rights" or something, though.  That might be cheaper.

Also, you can hire an independent band to reproduce the famous song with a few tweaks, and I think that falls under Fair Use.  

You'd do well to research all this.  I'm no expert.  :D

I believe that you can use 10% of a song, as long as its under 20 seconds

heck, i just cheat - i'm an unproduced screenplay kind of person, so i just slip in a music cue and be done with it!

i tend to use less well known bands, though, because my tastes in music are quite eclectic - using songs by bands like Tweaker and The Dresden Dolls is less likely to have some lawyer come sniffing round and throwing writs at you ^_^

if you're using songs in a produced piece, though, I'd generally recommend trying to make some yourself, or contacting someone who can, because it's just a lot less of a headache logistically, plus it doesn't swallow a chunk of your budget up!