Dude, no worries... I saw a picture of me with friends, and that was my motivation to start tanning... I was ghost white compared to them. I looked sickly. Looking healthy is a prerequisite for, well, a lot of things.
There will always be variations as you tan... Talk to the counter people and ask their recommendation. They'll probably recommend picking up a tanning lotion. Note that most (all?) places won't let you bring in outside lotions. So you're stuck buying their $20 crap. They usually have $5 "single serving" samples though...
You could also try a bronzer, which has pigment and basically dyes your skin... Careful around light colored clothing tho.
But even without these products, eventually when you build up tanning time, your tan lines will start to disappear and everything will blend into a more uniform color. Basically you have to wait for your "lighter" skin to catch up to your "darker" skin. It will, eventually.... Don't burn tho! Cancer is bad.
And yea I've only been tanning about a month and a half, so hopefully I'll start to see some more uniform coloring