Stretching ?!!

Hi guys, I’m a complete beginner runner aiming to run a 5k by April. I’m currently using the runna app, on week 3 and really enjoying it. Just wondering what stretches all you beginner runners find the best. I have noticed my left Achilles feeling a bit uncomfortable recently so any stretches specific to this would be amazing.

Also any other tips for beginner would be greatly appreciated, I’m thinking of buying a proper pair of running shoes in a week or two and was thinking maybe the adizero evo sl. Would u guys recommend for a beginner ?!

Thanks guys