Do some research into sites.
Start looking at photos of yourself, or take some selfies outside somewhere, of you smiling. Make an effort with your clothes and hair. Then doctor the photos, by cropping them so it's all you and experiment with colouring etc. Have about 6.
For your profile, think about your qualities. Are you kind, funny, hardworking? Are you genuine, honest?
And how do you fill your time? Are you a reader of books, like cooking, work on your car, watch movies and series? If someone were to get into a relationship with you, what would their life look like? What is someone buying into with you?
My experience of dating sites was very positive, in that I met decent people quickly and came off. Like you, I didn't know what to say, but just decided to be honest about what I do. I figured most people go to work and come home, and do stuff they like doing in their spare time. I like reading and studying guitar playing. I'm a home body so those who like going away every other weekend would need to know that so they didn't pick me. And the thing is, for every woman who wouldn't want your life style, another is living it but is lonely and hoping to meet someone.
When the time comes to go on dates, arrange coffee, dress and smell nice. Dont be late. Smile. Behave nicely. And my best advice? Ask them about their lives and listen well to the answers. And pay, that first time. And check they don't take advantage next time.
If you feel that anxiety could hold you back and negatively effect a potential partner, you owe it to both of you to push the boundaries until they are more comfortable for you both. I'd have a good think about that and resolve to take action if needs be.
And good luck!!!