Really should know this: how do I put a store's app on my phone?

[CatNamedEaster]

I can't seem to get my head around this. Do I start from my phone apps and search for the company name to download their app, or do I start from the company's website and try to find instructions for putting their app on the phone's home screen?

I don't know why I find it so hard to work out!

Go to the App Store on your phone and then type in the name of the app you’d like.

Go to the App Store on your phone (App Store on iPhone, likely Google Store or similar on Androids) and search the name of the store.

The store website might have a link, but the link will just take you to the App Store.

Play store on Android phones

Go to the App Store.

Done it! Can't wait to go to H&M and give the guy upstairs a shock by NOT saying "No I still haven't done it" - last time he offered to do it for me but I hadn't bothered to take my phone with me as I'm so crap with it. Thanks all