So this is my first time playing PSO2. I changed my class to fighter right after the prologue quest and I didnt get the weapons for the class and I cant find the npc that sells the first weapons. Am I supposed to continue with the basic class or am I missing something here?

In the Shopping Plaza there is an NPC that sells a random assortment of low rarity Weapons, and the inventory is updated at intervals (maybe every hour or half-hour); he is one of the two NPCs in the Shopping Plaza stores wearing red. Other than that, you can buy Weapons from Personal Shops through the Visiphone (the purple console in the lobbies).

@AndrlCh Shopping plaza that's what I missed ... Thank you so much.

@CharismaBrk No problem. Funnily enough, I myself actually didn't know about the Shopping Plaza area for the first three days of when I first started playing on the JPN server because I just assumed that all of the teleporters in the lobby were for Block changing.