If you want to add create “Register” or “Create an account” link in top navigation section then simply open customer.xml file in layout folder and you have to put below code in <customer_logged_out> area

<action method=”addLink” translate=”label title” module=”customer”><label>Creat an acoount</label><url helper=”customer/getRegisterUrl”/><title>Creat an acoount</title><prepare/><urlParams/><position>9</position><liParams/><aParams>id=”register”</aParams></action>