New Player searching for techniques or place to train special sudoku

Hi, everyone I am new to the World Puzzle GP. I do sudokus for a few years and I saw there are this site to play competition. I like to challenge me so I would like to play the competition. I saw today the examples of puzzles we have to solve for the competition but for some special Sudoku puzzles, I'm not sure how to solve them because I've never seen these types before. Do you know where I could find information or learn techniques for these different Sudoku puzzles? Or is there a place where I could practice once I've found some techniques?

I look forward to hearing from you and challenging myself in competitions.