HELP!! Introducing cats!?

My current cats are 2 young adult females: Homie and Tootie. Tootie is spayed, homie is not. I have just recently taken in a stray cat, now named Clover, that has been lingering around my house for quite some time. The stray is a female, and roughly the same age as the others. My mother said i had to keep Clover in my room, but my room is where Homie is constantly hanging out so now Homie feels like she's being pushed aside but I dont know what I can do.. Anyways, Clover saw Homie thru the door and absolutely hates her. She hisses, growls, yowls, and tries to attack her. Homie however has not hissed or growled once. They have never been in the same room with eachother yet. I honestly have no idea how to make them like eachother...ive never introduced cats to eachother and i'm lost. Clover is a sweetheart with humans, but so aggressive to other cats. I've taken Clover to the vet and gotten her checked out and have gotten shots and all. PLEASE help me. It's been about 5 weeks and Clover isn't getting used to the other cats...But that's probably my fault since I don't know how to introduce them to each other...My mother doesn't want anything to do with the cat and won't help, so guys please please pleeeeaase give me some advice..