It is very important to write a thank you note after your interview. Sending an email thank you note is just fine. If you want to write a handwritten thank you note too, that is ok. The important thing is that you remember to send one within 24 hours.
See example below.
Thank you for taking the time to meet with me today. I really enjoyed the opportunity to learn more about you and your company.
During our interview you mentioned…and I believe my skills….
I can be reached at (408) 420-8942 . I look forward to speaking with you about the next steps and I will also follow up with you in a few days.