Everything you do professionally and personally should be done with confidence and belief in your skills, knowledge and experience (unless you are wrong of course).
You are in your current position because you are good at what you do and you want to be even better. One of the prerequisites to success is believing in yourself by displaying confidence (which shouldn’t be confused with arrogance and cockiness) as you must believe in yourself before others will believe in you.
At the same time, make sure you stay humble about your qualities and achievements and let others evaluate the quality of your work and contributions. Self-promoting and self-glorifying are not attributes you want to be known for.