You can go to https://litecoin.info/Mining_hardware_comparison and see the hashrate corresponding to the equipment you have, assuming you know what is inside your computer. Actual results may vary, but usually this is a good estimate. Of course, if you overclock, you will get better hashrates, at the cost of increased power usage. If you want to actually mine, you will need to register at a mining pool and configure your miner to log in to said pool. The website you linked uses Java code to test hashrates, and this will not give accurate results (even for Bitcoin), as Java is usually slower than machine language.