Blow the trumpet in the new moon, in the time appointed,  on our    solemn feast day. For this was a statute for Israel, and a law of the God of Jacob.  So don’t let anyone pass judgment on you in connection    with eating and drinking, or in regard to a Jewish festival or Rosh-Chodesh or Shabbat.  Just continue doing what you know is the right thing to do! Nu?  Okay, you don't eat treif, you wouldn't think of Shabbat without your Manischewitz but,
What do you do on Rosh-Chodesh?
The Torah on the subject of Noah's ark says,  "And the waters decreased continually until the tenth month: in the tenth month, on the first day of the month, were the tops of the mountains seen." and "And it came to pass in the six hundredth and first year, in the first month, the first day of the month, the waters were dried up from off the earth: and Noah removed the covering of the ark, and looked, and, behold, the face of the ground was dry."
What do you do on Rosh-Chodesh? 
And HaShem spoke to Moses, saying, "On the first day of the first month shalt thou set up the tabernacle of the tent of the congregation."
What do you do on Rosh-Chodesh?
And HaShem spoke to Moses in the wilderness of Sinai, in the tabernacle of the congregation, on the first day of the second month, in the second year after they were come out of the land of Egypt, saying, "Take ye the sum of all the congregation of the children of Israel, after their families, by the house of their fathers, with the number of their names, every male by their polls"
What do you do on Rosh-Chodesh?
 And HaShem spoke to Moses, saying, "And in the seventh month, on the first day of the month, ye shall have an holy convocation; ye shall do no servile work: it is a day of blowing the trumpets unto you.
What do you do on Rosh-Chodesh?
For upon the first day of the first month began he (Ezra) to go up from Babylon, and on the first day of the fifth month came he to Jerusalem, according to the good hand of his G-d upon him.
What do you do on Rosh-Chodesh?
And it came to pass in the eleventh year, in the first day of the month, that the word of the HaShem came unto Ezekiel.
And it came to pass in the seven and twentieth year, in the first month, in the first day of the month, the word of the HaShem came unto Ezekiel.
And it came to pass in the twelfth year, in the twelfth month, in the first day of the month, that the word of the HaShem came unto Ezekiel.
What do you do on Rosh-Chodesh?
In the second year of Darius the king, in the sixth month, in the first day of the month, came the word of the HaShem by Haggai the prophet unto Zerubbabel the son of Shealtiel, governor of Judah, and to Joshua the son of Josedech, the high priest.
What do you do on Rosh-Chodesh?
Before you can do anything, you will need a Hebrew calendar.  We'll send you off for a calendar in a second, but first, don't be a schlemiel, first put our web address in your favorites, lists, etc.  Okay, if you promise, emis, you will come back and visit again, you may click here and off you go!