i need his family tree for a school project.

Ok I assume you mean Ramsess II. Here it is.

I can only write this out for you, you will have to put it into a tree yourself.

His grandfather was Ramses I, his father was Seti I. Seti had four children that we know of. An older brother of Ramses II who died young, Ramses II, A sister called Tia, who confusingly married a man called Tia, and a sister called Hentmire, who some say was his daughter but it is more likely she was his sister.

Now Ramses II had numerous children as we know and I don't have the names of all of them to hand.
In terms of sons their names were Amenhirkhopeshef, Parahirwenemef, and a load more by Nefertari but I can't remember their names. They don't inherit the throne though.
By his second Great Royal Wife, Iset-Nofret, he had Ramses, Khamwaset (High Priest of Ptah at Memphis), and the 13th Son was called Merneptah. He would succeed to the throne on the death of his father.

As for daughters, his eldest daughter was called Bintanath, by his wife ISet Nofret but the next four daughters were born to Nefertari. They were Baket, Nefertari II (Both died young we speculate), Meritamun ( Who contrary to popular belief wasn't Nefertari's eldest daughter) and Nebtauwi. Then comes Iset-Nofret II by his wife ISet-Nofret, and then Henutawi by Nefertari again. He had hundreds of children but these are the important ones.

Now Ramses married several of his daughters and his sisters. He married Henutmire, Bintanath, Meritamun and Nebtauwi but only with Bintanath does he have a child. This was a little girl. Not much is known about her but it is speculated that she was also called Bintanath and went on to become a secondary queen of Merneptah, to whom she was both sister and niece.

Now Merneptahs chief Queen was Ramsess II 6th Daughter Iset-Nofret II. and she gave birth to the Crown Prince Seti-Merneptah (Later Seti II) but there was a squabble over the crown. Instead a younger brother of the Crown Prince seized the throne while Seti-Merneptah was possibly away on military duties. His name was Amenmesses and he was a son of Merneptah by a women called Takhat. Amenmesses married a woman called Baketwerel.
When Set-Merneptah ascended the throne as Seti II he had 3 wives that we know of but the Chief Queen appears to have been Twosret. She gave birth to the heir, another Seti-Merneptah but he died before his father. Another wife Tiaa gave birth to Ramses-Siptah who would succeed his father. He had a third wife called Takhat II.
Ramses-Siptah died after just six years on the throne and Twosret took the throne as female pharaoh. After her the 19th dynasty ended.

Few that took work:-)

By the way, Rameses second daughter is called 'Baketmut' not just 'Baket' like I have stated.

Oh and I forgot the Hittite brides. Late in his reign Ramses II married a Hittite bride who was given the egyptian name Maathorneferure. She was also given the title of Great Royal Wife although this may only have been at the insistance of her father. It appears she never actually served in the role of Great Royal Wife. This role continued to be carried out by Bintanath and Meritamun.
There was also a second hittite bride but her name is uncertain. She is mentioned in the 'Bentresh' stelae when te daughter of the Hittie king is ill and sends to egypt for help but her name is unknown.