If your daughter is the one that was charged, you would not be representing yourself, you would be representing her. Since you are not a lawyer, that is probably why the judge is telling you to get a lawyer. It's a very good idea, anyway. What happens in the case could affect your daughter for many years to come - you want to know all the possible consequences of a guilty plea, and all of the other options available to her.
I recommend that you contact a lawyer as soon as possible. If you don't know a lawyer, you can call the Houston Lawyer Referral Service 713 308-8585
First, only a licensed attorney can represent your daughter. Parents are not allowed to appear as counsel for their children.
Second, your daughter (with the assistance of her lawyer) will decide whether to plead guilty or not. Parents don't get to decide how their children plea to criminal charges.
Start interviewing local juvenile criminal defense lawyers. Schedule a consultation and ask them to explain the process. Find out what to expect in terms of possible sentences etc.
I agree with the above answers. This is your daughter's decision and she needs to decide with the advice of an attorney whether or not pleading guilty is in her best interests. The judge is doing the right thing by not allowing you to represent your daughter as you have an emotional stake and may not understand the constitutional, legal, or evidentiary issues involved. The problem is that allowing a mother to represent her daughter could cause your daughter to make a decision that is in the best interest of your relationship with her rather than a decision that is in the best interest of herself and her future. That is why a representative needs to be provided or retained. Good luck.