You can install Android Market and most of Gapps, search the forum for more info/tutorials.
But it's a bit messy, may even cause problems if you try to install the wrong package. Instead, you can use GetJar, SlideME, 1Mobile or Amazon (if you are in the USA). It's as simple as download the app using the built-in browser and install their market app. GetJar even offer some paid apps for free, with new one added from time to time.