Pavani,
1) You can create a stereotype by right clicking on the model and going to “Create Child–>Packaged Element — Stereotype” from the outline view.
2) To add existing stereotypes, can you try these steps :
a) Create uml2 diagram
b) Right click on the uml2 from outline view and select, Apply Profile
c) It will show default profiles, select any of the profile now, If you create class or package
and observe, you’ll see available stereotypes within the properties stereotype tab.
Let us know how it works for you.