This is not something that is to be attempted by an untrained person, it's not difficult and minor adjustments can be performed when you are familiar with what you are doing, but it is not something I would recommend for a novice player who is not sure yet of what he prefers, and experienced enough that he tried guitars with a variety of different actions. If the action is brought high, a truss rod (the steel rod inside the neck that counters the forces of the strings tension) adjustment may be required, the neck could be damaged if this is neglected, creating "buzzes" or other undesirable effects on the playability of the guitar. The "action" of a guitar refers to the distance of the strings to the fret board. The action is a function of the location of the bridge in relation to the saddle and the nut and its height off of the body of the guitar. The saddle holds the ball end of the string, the nut is a notched bar that divides the fret board and the head stock, these are both stationary and cannot be moved. There should be mechanisms (usually screws) that allow the bridge to travel parallel or perpendicular to the body of the guitar. To bring the action up, raise the bridge, to bring it down, lower the bridge. depending on how far it is moved, it is likely the intonation will be affected, and in order for the guitar to have proper tonality the bridge may have to be moved parallel to the body of the guitar, either closer to the saddle or moved forward in the direction of the nut. With most electric guitars, this can be done with each individual string (within the confines of the threads that are the width of the saddle). With many acoustics this parallel to the body adjustment is impossible, and a less than desirable intonation may be something the player needs to live with as a sacrifice for his desired action. As you can see it is a pretty technical adjustment that varies greatly by model, there is more to it than I have touched on, there are many things at play here that are affected by the most minor of adjustments. This tedious trial & error procedure should be done by an experienced person. Every guitar is different, even if they are the same model, two strats could feel, play and react to action adjustments completely differently, getting your axe "set-up" by a professional from time to time is a great way to ensure a long and better life for your guitar, it doesn't cost that much & it'll sound and play better too!