How do Mission Pass work?

Hello! I want to know how do Mission Pass work and how do you get them and leveling them up work? I tried to understand it in FortNite and Paladins was confusing me because that was my first f2p game. Can someone explain in this game how do Mission Pass work in PSO2? Thank you for your help.

(Xbox control scheme)

Press start to open the menu, in the upper left you get a window which shows various statistics. Toward the bottom of this window is mission pass details, including present season and the tier you've presently reached.

Press X to see your mission list from here. Of these, Daily Missions, Weekly Missions and Tier Missions all show as giving tier points (the yellow star on a purple square). Tier Missions give the most by far, but like Weekly missions seem to be time-limited with the present season already half over.

Press X again to see your mission pass directly. It'll show your tier and any rewards you can claim. You need 10 stars to advance in tiers and you level automatically.

Ok. Thank you!

And I have collected some weapon medals how and where do I use them? I'm looking in the Shopping Plaza but I can't find anywhere to use them.