Here’s a useful video on how to read and pronounce four of the tones in Mandarin (vid is about 1/2 hr long):
Ni Hao Children's Community Mandarin Chinese Language Education Programme
A chance for your child to learn Mandarin Chinese through group social interaction and fun experiences
Here’s a useful video on how to read and pronounce four of the tones in Mandarin (vid is about 1/2 hr long):