Boil pasta in plenty of well salted water according to package directions. The reason I suggest so much salt is because most of it ends up down the drain.
Drain pasta, rinse in cold water, drain again and tip into a huge bowl. Add frozen peas immediately to the pasta and toss until the pasta is cooled and the peas are kind of 'blanched' due to the heat of the pasta.
Cool before adding everything else and tossing gently to combine. Serve! If you need more salt (which is possible) taste and adjust accordingly.