Language learning can be very difficult for students with a fix mindset so adopt a growth mindset. Everyone can learn a language, but it is not easy. In a classroom, it is easy to feel dumb when comparing yourself to other students who have more practice with the language or with a textbook that isn't at your level.
Learning a language is like running. When you first try to run a mile it is very tiring, but if you do it every day it gets easier and you can run further and faster. When you first start a language, all the words may sound the same and seem impossible to remember. Just keep practicing with material that is challenging but not frustrating. If the textbook seems too hard, remember you don't have to understand everything perfectly to improve your language skills. In fact, just understanding the gist or learning a couple of new words per passage may be what your teacher intends.
Supplement your textbook with lots of videos and picture books. YouTube is an incredible source of materials for any level. Also, don't worry too much about speaking right away. Lots of input is key in the beginning. (Krashen)
Here is a guide to using YouTube from a man who speaks many languages.
He also has a blog post about this topic.