How Do I?

It's pretty simple.
1) Turn the LoomPal™ on and select a Pattern.
This is assuming it has been configured for your loom (easy) and your pattern (WIF) has been saved on its SD card. If you have previously saved your place, you just press Resume and everything is just like you left it.
2) Select Weave and start weaving.
There's also a variation of Weave called Lift Mode which is exactly the same except the liftplan for each pick is shown, which is handy for dobby looms and essential for table looms.
Touching the screen brings up a menu to make changes to the dynamic drawdown such as choosing cloth or draft. You can choose whether you want a warp based or weft based drawdown.
Instead of pattern, you can select tabby or plain weave. Tabby picks can be inserted between pattern picks, if desired, or you can just stay in plain weave until you're ready to go back to the pattern. Tabby and plain weave picks are in addition those in your pattern. You can enable them if you want. You can also set them to be whatever you like, but the default is A = odd, B = even.

16s 16t Tieup Example
The Repeat option lets you select from looping, halt and auto-reverse. 
Selecting Unweave reverses the direction and takes you back through the exact sequence used for over the last one hundred plus picks. This includes jumps, ranges, inserted tabbies and sections from other files.
Picking Jump lets you directly jump to any pick in your pattern. Great if you need to move more than a couple picks, otherwise you can advance one pick per touch of the screen.
And there's Info/Alarms. This shows or resets the project time, the number of picks and repeats, the length (in/cm) and allows you to set Ranges. Ranges let you iterate over any part of your pattern any number of times (you can set an alarm for any number of repeats). When you're done, just cancel the Range. Other alarms are any pick count, repeat count and a cyclical alarm every so many picks.
And last, but not least, is Save. Touch this often to save the current state of your project.
Pressing OK gets you back to weaving.