星期一，星期二
Monday, Tuesday

星期一、星期二、星期三、星期四、星期五、星期六、星期天。

The Chinese week is simply counted. 星期 means 'week', and you add the number of the day to it: Monday is day one, so 星期一; Tuesday 星期二; and so on up to 星期六 for Saturday. Only Sunday breaks the pattern — there is no 星期七. It is 星期天 in speech and 星期日 in writing. Note that the 一 of 星期一 keeps its own first tone, yī, as it does whenever it names a date.

一九九九年十月五号。今天是十月五号。

A Chinese date runs from the biggest unit to the smallest: year, then month, then day — the reverse of the English order. The year is read digit by digit, not as a whole number: 一九九九年 is yī jiǔ jiǔ jiǔ nián. Months are just a number plus 月: 一月 is January, 十月 is October, 十二月 is December. Days are a number plus 号 when you speak, plus 日 when you write: 五号 is the fifth.

今天是星期四。今天星期四。

Both of these are correct. Before a weekday, a date or a clock time, everyday speech often drops 是 altogether: 今天星期四, 明天十月六号. Keep 是 when you want to be clear or emphatic, and keep it always in a 吗 question with a date: 今天是星期三吗？ This dropping happens with times and dates only — 我是学生 never loses its 是.

今天是星期四，十月二号。明天是星期五，十月三号。

Say today's weekday and today's date aloud, then tomorrow's. Then run through the whole week once — 星期一 to 星期天 — and say what you do on each day, using the verbs you already have: 星期一我上课。星期六我买东西。星期天我不上课。 Finish with your own birthday as month plus 号.