Hi. Congratulations on getting through school as a single mother. That is a very admirable accomplishment.
You apply to schools AFTER taking the LSAT. Your first step will be to register with the LSAC (Law School Admission Council). http://www.lsac.org/
There, you can get a lot of information about law school and the LSAT, including a copy of an actual past LSAT with grading key.
You can take a weekend prep course for the LSAT, however I would suggest first checking out the LSAT board on this site and doing a little self-study. You will get a better idea about where you are and where you need to go that way.
Again, congratulations. I have two small children and I just finished my first year of law school. It is a lot of work, but so rewarding.