I would suggest going to www.uspto.gov for guidance on filling out trademark applications. The trademark office website has good resources to help you fill out forms and you can search existing trademark files and view what others have submitted.
Do a trademark search, select a mark that you believe is relevant, then select the button labeled "TARR Status" and then select the link "Trademark Document Retrieval" near the top of the page. From here you can review submitted documents.
However, I would strongly suggest that you consult an attorney instead of submitting a trademark application on your own. Although it may seem like a simple application in some respects, small mistakes can be very costly down the road.
The complete prosecution files of recent U.S. trademark applications can viewed online without charge in the TDR (Trademark Document Retrieval) database at the website of the U.S. Patent and Trademark Office. See link below.
Basic information about the federal process of registering trademarks is available at the other link below.
You should know that it makes all the difference in the world whether or not the business has already started to use the trademark in interstate commerce. If so, then the application can typically be based on "actual use." If not, then the application would be filed on the basis of "intent to use."
Also be aware that an official at the trademark office, a Trademark Examining Attorney, will review the application before it is allowed. Often the Examining Attorney will have questions about the description of the goods or services for which the mark is sought to be registered. And the Examining Attorney may find the application to have a likelihood of confusion with an already-registered trademark. After the application is on file, it is possible to make certain kinds of amendments to the application, but not others. In the latter situation, the applicant will have spent the government filing fee of $275 - $325 in vain.
The range of prices for the government fee comes up because an applicant can get a $50 discount for selecting one or more "canned" descriptions of the goods or services, and thus qualifying for the TEAS-Plus version if the application is filed online. Also note that the government fee is charged for EACH "class" of goods or services.
I write only to caution against making any significant branding decisions without first seeking the advice of a trademark attorney.
The likelihood of selling a good or service is a function (in equal parts I think) of price, need, the quality of what is being sold, and the image that consumers have in their minds of what is being sold. It's tragic that great products and services with a lousy brand image fail as often lousy products or services with a great brand image succeed.
So when (or preferably before) you come up with a branding strategy you need to make darn sure that you can lawfully use whatever it is that you want to use as your brand identifier (your trademark). That's because, hopefully, the trademark will be the vehicle that will carry, and which you will use to build, your product's reputation among consumers. If you join the ranks of those don't invest in clearing the rights to your brand identifier, you may have abandon your entire branding strategy and (1) incur that business set-back and the costs of starting anew (if possible) and (2) potentially paying a settlement to whomever first began using your nifty source-identifying trademark.
We all know that it's difficult to build name-recognition, goodwill, buzz, brand value -- whatever you want to call the attractiveness of your product or service to consumers. It always amazes me, therefore, how often entrepreneurs invest considerable time and other resources in that exercise without first making sure they can lawfully do so.
All three answers are excellent. I only wish to underscore the importance of speaking with an attorney who practices trademark law before you file your application. There are properly filled out applications on the USPTO's TDR system, and then there are applications that never should have been submitted in that form also on the TDR system. There is nothing on the system to indicate to you what is properly done and what is not. Also, trademarks are not granted just because someone applies for the mark; it's actually a fairly high standard that a trademark or service mark must reach for registration. While some marks go flying through the Office, there are marks that need to be prosecuted more fully.