well lets start with equipment... Most hip hop producers use a mpc 2000 as there sampler as its a sampler/drum machine/sequencer. but if you have a decent PC you wont necesarly need one. you should look into getting these two software applications "sonic foundry acid" and "fruity loops".
Origanally hip hop artist had no money for there musical instraments other then records and turntables... they would match up an old beat from an old R&B song to a newer beat from a beat record... today not much has changed other then producers work with samples instead usuing the old turntables. so think about going to the library and getting lots of old music sample a a few loops that sound good once you have your sampled loop you can take it into acid and decide what tempo you want it at. Hip hop generally runs at about 80-110 beats per minute. next thing is into creat a feaw of your own drum loops and textures in fruity loops. Fruity loops will take the place of and outboard drum machine (like the mpc 2000). Its more pratical to use this then a drum machine because you can download hundreds of drum hits from the web. one of the most comanly used old drum machines in hip hop is the Roland 808 so you'll want to download some of those samples. I"m sure youve hear that machine alot, it accounts for that really low bass hit that sustains for a bit.after making your additional beats bring thos into acid and start aranging the samples you have to get more of a compisition going. after that you may want to add a synth line ( having a synthasiser would be very helpfull at this point) to sample and add to it and maybe some wierd effex samples or some wierd vocal samples from a movie if you like that. thats prety much it... one thing to remember is Lo Fi, that means dirty sampls work well and older more retro sounding drum machines and so on, you don't want to use the most hi tech sounding synth patches ....or maybe you do hehe... there is no exact right or wrong way to approch any musical style you have to find the process that works best for you.

one more little trick to help is to dirty up ssamples if you get them from cds instead of old vynal is to put them to audio casset and then resample them, you can bounce a sample back and forth from tape to PC a few time and it will degrade the audio to make it sound more lo-teck or lo-fi as they call it these days.

I really could keep going I think but I don't want to confuse you by going on and on. so I hope this helps or at least gets you started.

taos