1.) The app needs a Bluetooth OBD2 adapter to work. The adapter is small and plugs into the diagnostics socket on the car which gives your phone access. You can find a list of adapters on:
http://torque-bhp.com/wiki/Bluetooth_Adapters(Garmin EcoRoute HD adapters not supported)
2.) If you buy one of the cheap china OBD2 ELM327 bluetooth adapters from ebay / amazon, then make sure you have a good returns policy with the seller. Some of the best reliable OBD2 / OBD adapters are the Scantool.net adapter, the OBDKey, and PLX Devices, OBDLink, Bluetooth, ELM327 and other adapters are supported - search on google for them
3.) **Polite Note!** There are currently a lot of clone adapters circulating that are broken/not working on the CANBUS protocol - if your vehicle isn't working, check the adapter if it's a clone(it may work on older vehicles though)
4.) You should be seeking support from the author via their Google Play page where I found points 1-3.
If you're not willing to tell us what you have done, you're probably not going to get a reply. You'll get out of this thread what you put into it. I suspect your problem is somewhere in 2 or 3.
Seriously, you have given us nothing.
...you can't create a log.
CAN YOU EVEN CONNECT?
DO YOU GET ANY DATA?
DID YOU BUY THE PRODUCT OR DOWNLOAD IT FROM THE PIRATE SITE?
Every little bit of information you can offer helps us help you.
Good luck.