Once you understand it, then it's easy. But I was lost in the beginning. The following document really helped me. I'm not sure who wrote it.
To set up parameters for your Lipo, first determine how many cells you have. You hear terms like 2s3p or 6s4p, don't let them confuse you. Just concentrate on how many "s" you have, that would be your cell count. The two examples above would be 2 and 6 cells, respectively.
Then your capacity is determined by the "p". Usually pre made packs will be labeled with capacity, such as 7800mah for a 4p pack of 1950mah cells. If you build your own packs, just multiply the capacity by number of "p". For example, a 4s4p pack of 1950mah cells would be 4 cells at (4x1950) 7800mah, even though 16 cells were used to build this pack. If this sounds confusing, just set the maximum capacity setting to 0mah (see below) to disable it.
On to the charger.
With the charger powered up, hold both buttons down, then let go of the left (-) button only. This should put you into the configuration menu.
Press the right (+) button will scroll you through the type of cells. Scroll through until you see "LiPo". Now press the (-) to go on to next step.
Now you are at cell count. Press the right (+) button to select the cell count. If you go past your count, just keep on going until it starts over. Make sure you get the cell count right or else it may damage your pack. Now press the (-) to go on to the next step.
Now you are at the maximum cut off capacity menu. This is an optional safety feature to cut off your charger in case the charger fails to detect the peak. Ideally you want to set the capacity to match that of your pack, but your battery capacity might not be listed as one of the selection. Press the right (+) button until you see the capacity that closely resemble your pack's capacity. For example, my 4s4p pack has capacity of 7800mah, but it's not listed in the selection. So I set it to 7500mah to have it cut off right before it gets full. Note: You could disable this feature by setting the capacity to 0 mah. Now press the (-) to finish the configuration.
Now you should be back to the "Go" menu. At this point, plug in your battery will automatically begin the charge. The maximum charge amp is listed to the right of "Go". You can increase or decrease this value using the (+) or (-) button. This setting can be done before or during the charge.
The charger will begin with .25amps, slowly revving up to the maximum amp in a few minutes. Depending on the maximum charge rate, the charger will stay at this maximum amp for a certain duration until near the end of the charge. By then, the amp will decrease slowly until the pack is peaked. For my 6s4p 7800mah pack, it took an hour to charge about 7000mah at 8amps max, with almost another hour to peak the pack. You could certainly fly the pack without wasting another hour trying to squeeze the last 800mah into it. According to Charlie Wang, this will actually increase the life of the pack.
You will only have to do these settings once. The charger will remember the settings next time you power up. Only bad thing about this is if you have to charge other type of batteries, you will need to set it again.