I have no idea what you why you would start with your birth certificate to change your name except that you will need to attach a copy to the name change petition. In any case, all you have to do is call the circuit court clerk's office and make sure they have the forms to change your name. If they do, then go to the clerks office and file them. If not, download them here, fill them out, and go to the clerks office to file them:
http://www.mdcourts.gov/family/formsfinder.html#k.3.1m.2a.1m.37You will need to pay a filing fee and fees for publishing the required notice. The court clerk can give you a better sense of what the total fees are and the length of time it will take in your county. In some counties (e.g., Montgomery) the courts routinely allow notice to be given by posting the notice on the courthouse bulletin board instead of publishing it in a newspaper, so ask the clerk about that too. In Montgomery County there is a form for that as well. I am not aware of another county that does this, although I do know of several others that don't.
There are also numerous websites that explain the process at no charge, including some geared specifically for trans* people, that come right up with simple google searches.
I hope this helps!