I'm getting the nikon 300d but I don't know what lens to buy?

I like to take detailed photos of animals and people

Nikon never made a 300d. They make a D3000, D3100, D300 and D300s.

Animals, depends on how far away and what you want to spent. Same goes for people

To get close to animals you'll need at *least* a lens which goes up to 200mm focal length, and that's just for animals that don't get to spooked by humans.

I suggest you start reading
knowledge is power

Portraiture and street - AF-S 85mm f1.4. DC-Nikkor 105mm AF.

Wildlife - 300mm f2.8 VR, 400mm f2.8 VR.

I presume you mean the D300.

To start with you might want a general purpose lens if this is your first foray into DSLR's - something like the 18-105mm.

For street candids, studio work & other portraiture I use a 50mm f1.8 or a 85mm f1.8. Or in zooms I have a 24-70mm f2.8.

You might want a macro lens (which can double as an excellent portrait lens) - the 60mm f2.8 or 105mm f2.8 are both good.

If you want reach, for wildlife, then give the 70-300mm a go - not the best lens quality, but fast telephotos are expensive glass & I don't know what your budget is.