For your CDL Training you do not have to buy anything to get the knowledge you need to past the written part of the CDL Tests. All information that you need to know. Is in the booklet that each state has for the required federal regulated testing. No matter what state your booklet is in the information is the same because CDL training is federally regulated. All it has is a different cover on it. To see the Maryland book click here
Now there are places that sell sample test and some that are free. That can help and build your confidence . I will suggest a couple for you. This site has free test questions that should help. click here for free test
If you would like to read a ebook to inform you on what you need to know out in the trucking world. I thought this book was really good.For a book on trucking click here
Lets talk about what what the test covers and what you need to know.
More on CDL Training written test
The first part in General knowledge test. This part of the test is fifty questions.and each sub part of testing will have part of the general knowledge test questions. The General knowledge test you must take.
The other five endorsements, Air Brakes,Combination Vehicles, Double and Triples, Tanker,Hazardous Material, test. These endorsements you do not have to take unless your going to drive a vehicle that requires that particular endorsement. For example to haul Hazardous Material. You will be required to test for that endorsement on your license. As a new driver I suggest you should get all the endorsements. This will make you qualified for more job openings.
If you get your Hazardous Material (Hazmat) you will have to under go a back ground check and finger print check. Endorsement will not issued until all is cleared with TSA. Transportation Security Administration
Chances are that you will need TWIC card Transportation Worker Identification Credential no matter who you work for. If the company has any connections with over sea freight.If you drive a Tanker you will need a TSA background check and be issued a TWIC card. For more info click here
The back ground involves finger prints and sign some documents to authorize the background check that they will be doing.
My link Trucking schools will give you more information on where you can get training.