E-textbooks are one of the commonly used sources to learn programming, in the domain of computer science and engineering. Programming related textbooks provide examples related to syntax, but the number of examples are often limited. Thus, beginners who use e-textbooks often visit other sources on the internet for examples and other information. Adding dynamic information to programming related e-textbooks such as additional information about topics of discussion and real-world programming examples could enhance readers' experience, and improve their learning. Hence, towards enhancing user experience with programming-based e-textbooks, we present "TAnnotator," a web-based portal that dynamically annotates computer-programming based e-textbook, "The C++ Tutorial," with related programming examples and "tooltips." The "tooltips" aim to provide further knowledge to the readers about various concepts being discussed in textbooks by providing related facts adjacent to the text of the topic in the e-textbook. "TAnnotator" has been evaluated to assess the usefulness, user experience and complexity using UTAUT2 model through a user survey with 15 volunteers. The results of the survey indicated that "TAnnotator" was useful in providing additional knowledge on top of the e-textbook.