I'm assuming it is standard cask conditioned ale (I.e. not racked bright) and therefore will want a fair amount of settling (24 to 48hrs or so minimum, really depends on the brewery and something you get to know through experience. The longer the better!). After settling it ideally it wants venting for at least 48 hours or so before serving but you can drink it straight away if it has cleared it'll just taste a bit 'young' and might be very lively. Any beer I take to events (Leafers for example!) I usually serve it upright anyway (but I try and get it bright). That way you can take it from the top as it clears (but I use a beer engine) and it means less time waiting (arriving Friday for a weekend event isn't ideal!)
If you got it from the local pub they should be able to give you a tap and a couple of spiles (pegs). The best way to serve with no equipment is lie it on a stillage (some wood will suffice, try and get it pointing slightly downhill) and leave it to settle for a day or two. It also wants to acclimatise to the room temp as well. Then vent it (soft spile in the side) and tap it straight away (saves disturbing the cask again later). Let the beer 'work' for 48hrs or so. You can keep checking by drawing a bit out of the tap and looking at the condition (and of course tasting!) Obviously tapping and venting should be done with one swift firm blow with the mallet!
Again depending on the brewery/beer it might be very lively, so as it conditions it might spew some out over time (or sometimes even fire the spile out if it isn't tight!) Either sit it somewhere you can mop up later or make provision for catching any that comes out. Even in our cellar at the club I work at (which is flagged) we use a vent pipe into a bucket when first venting to catch anything that comes out. And it wants to be around 9-12°C or so ideally
At the pub I used to work at in Sheffield we had loads of cask lines (13 to be exact) and cellar space was at a premium so casks were upright. We vented all our casks through the tap hole and extracted using a 'caskwidge' which is a flexible pipe with the end on a plastic float. It took the beer off the top all the way down the cask.