Prayer in congregation is twenty-seven times better than praying alone. Muslims stand shoulder to shoulder in straight rows behind one imam — rich and poor, all equal before Allah.
The imam is there to be followed: say the takbir after his takbir, bow after he bows, and never move before him. If he errs, men say "Subhan Allah" to alert him.
Friday is the best day of the week. Jumuah prayer replaces Dhuhr for men: two khutbahs then two rakat. Its sunnahs include Ghusl, wearing the best clothes, going early and reciting Surah al-Kahf.