Possession of Marijuana on a first offense is an unclassified misdemeanor punishable by up to 30 days in jail and/or a fine of up to $500, and your license on conviction is suspended for six months. A second or subsequent conviction is a Class 1 misdemeanor punishable by up to 12 months in jail and/or a fine of up to $2,500.00. Your license on conviction is suspended for six months. A person convicted of this may ask the court for a restricted license. You should contact an experienced criminal defense attorney for help with the case. The attorney may help you get the charge dismissed or reduced to a lesser offense, depending on the facts and your record.
A true first offense of marijuana may qualify for a diversion program where you do community service, participate in a drug education/treatment program, and avoid new charges. After a while the case would be dismissed without having a conviction on your record. Unfortunately, it would still require your license to be suspended for 6 months. Most judges would allow you to have a restricted license.
You should consult with local counsel about the facts of your case, any possible defenses, and any other options that may be viable in your local court.