First you have to fill DS-160 form (https://ceac.state.gov/genniv/) as a principal applicant. Later, you will see “add dependent” option for your wife.
(Assuming that you are visiting India) Then you will need both DS-160 confirmation numbers to create a profile on [http://portal.ustraveldocs.com/?language=English&country=India](http://portal.ustraveldocs.com/?language=English&country=India)
TWO dates (OFC & interview) selected by you will be for your wife too.
You will need all your H1B/H4 related documents (Approval notices, job appointment letter, salary slips, LCA, H1B/H4 application packet, etc...) along with visa interview documents, marriage certificate, etc...