Noob Question

1) Hit F3 aka the Criminal Underground button at top of screen.

2) Enjoy.

Okay, next question: how do I travel to other solar systems? There are like 4 right now and I can't seem to leave the one I'm in right now.

You can also go to the Keybindings page on the options screen. Look for Buy Metal and Buy Crystal. They're bound to something initially, but I changed them to F5 (metal) and F6 (crystal).

It's a lot easier to just punch the button a few times than have to muck about with the black market UI. Plus you don't lose track of what's going on in the game.

Edit:
Travel to a new solar system by researching the appropriate drive technology in the military tree. I don't know the names offhand, but it will say something to the effect of "Allows travel to distant star systems". After you've researched it, move your fleet to a star, then right click the star you want to go to.

Research the "long range hump drive" technology in the civilian tech tree. Then, just as you would with a planet, click your ships to another star (they have to travel from sun to sun).

I'm horrible at this game. :..(

I'm not happy at all. I have my fleet for defense at the star and they just jump where ever they want without my fleet even touching them.

Star jumps are semi-predictable. Draw a line between the two stars as if it was a regular jump lane. Position your forces in the general area where that virtual jump lane would end in your star's gravity well. When the enemy fleet transitions in, you will be in the general area and close enough to interdict them and inflict damage before they can leave the gravity well.

If you want to be REALLY sneaky, manually move your fleet slightly outside of the radius of the gravity well (just outside the circle surrounding the star) and point them towards the star itself. If you estimate the enemy's arrival location well enough, you'll get several seconds of uncontested weapons fire directly into their flanks. Ouch.

Oh yeah.