Welcome to Esoth's Hunter Tools!
Head over to the Calculator to compute DPS and generate some statistical analysis. Right now selecting equipped gear is not supported, but I hope to support it in the future (unfortunately it may have to wait until after launch when I can see how it comes in from the WoW Web API).
Gear stats should be entered from gear only - not specialization attunements, mail specialization, or base stats. This will be computed separately.
Until the expansion hits, you are probably better off using the default stat values, which should match the starter gear for premade level 100s.
Visit the change log for the latest changes.