My (03) 206 has a fault, anyone help??

I have been in and out my car all day today and after a journey of running a friend home my car started making a hideous noise in which i thought it was the workmen outside. After turning down my radio i noticed it to be coming from the car and then the 'stop' light on the dashboard started flashing, but i managed to get home. Just read the mannaul which hasn't really answered but just wondered if anyone can help me? Im a 21 female that has no idea about cars :(