First you need to decide what to mine. The web site whatomine.com is a good place to start. Input your estimated hash rates for your 290 and the it will tell you a good coin to mine. Then go out and get the appropriate Miner software for that coin/algo. Then find a pool that supports that coin, sign up or look at their help pages. Setup your .bat file and start mining.
My main question is how do I set up the actual miner? How do I know what my estimated hashrate is?
Download the Nicehash miner legacy version and run the benchmark. That will give you a good idea of your rigs hash rate for various algorithms and you can use that to calculate your profitability on whattomine.com