Does anyone knows how to create hair for toddlers like the little black girl from "Rugrats".

Hair isn't a good beginner project - it takes a fair bit of meshing and UVMapping knowledge, and is very time consuming and frustrating even for experienced modders. I suggest you start with something simple, such as an accessory, and work up from there. Once you know your way around Milkshape and either CTU or TSRW, then you can have a go at hair!

For various tutorials on meshing and texturing in general, go Create -> Sims 3 -> Tutorials.