I have been working as a technical consultant for a company. I am planning to use my travels (mileage) to the company from my home as deductibles. I have been recording the dates for the travels. However I still do not understand how the info in my notebook will be considered as a proof for the travels. Do I need additional documents to prove the travels?

Thanks,

The commuting miles from home to work/office and back are not deductible. If you go to meet clients from office and return back to office, these miles are deductible.
For 2012, the standard mileage rates for the use of a car (also vans, pickups or panel trucks) are:
55.5 cents per mile for business miles driven.

For business mileage in general if you keep a contemporaneous log of mileage the IRS will accept it as proof. Of course they may want to review it - and if it seems that all your mileage is "business" without a reasonable mix of personal use they may question it.