Hey,
For doing a PhD in the US
1.Browse through the department webpage of the univ.s. you are intersted in.
2. look fo rthe requiremnts they ask for..usually they are GRE, TOEFL, SOP{statement of purpose} and filled in applications.
PhD s in chem & biochem 'll give you financial support usually.
If you have anyother doubts send me an email : synergid7@yahoo.com
good luck
raaj.