vue - Training Young Walnut Trees, head-pruning vs. leaving them un-headed

1. i planted walnut tree last year from walnut seed, should i prune it or not to touch it? I got it from nortern ontario man and he told me the fruits are very small a bit larger than hazelnuts.
2. i have a house in Cathedral Ca. 92234 i have a walnut tree is about 17 to 18 feet like 8 to 10 year old never have a single walnut why? can you help me.
3. this is an excellent video well done heading in my world [ and trust me I have seen the results in many different species ] is a major no no . I wont go into reasons why, well done on this video,, well done , I say. Buckin' Billy Ray