As a U.S. citizen, you are free to say what you want, wherever you want. Criticism of the government, sports, and other forms of speech is a sacred right that you now have.
You can now cast a ballot in, local, state, or national elections (ex. For the President). See the "Relationship Between Voting and Citizenship" Tab for info on how to vote legally.
You can now apply for government positions such as the UPS (Postal Service), FDA (Food and Drug Administration), etc.
As a citizen, you can run for local, state, and national elections! Local positions include county boards, public safety committees, and mayorship. State positions involve the state senate and governorship. National positions include the presidency, vice presidency, and both houses of Congress.