Melee mercenary?

https://preview.redd.it/a38wsjswrm5e1.png?width=260&format=png&auto=webp&s=23999cb75808292bc91edcff06127d0f5f06b171

this is in the skill tree of the mercenary

im new to poe, im more used to skill trees like grim dawn or diablo 2 so im not sure how could i turn my mercenary to be melee, and if so, what would be the difference with a warrior?

please can anyone guide me a little bit to understand better how to make a build?

so far i have been playing with the crossbow, im lvl 20 and im managing, only have died 2 times and both were a stupid error (didnt notice that the skelletons with shield in the cementery were returning my range shoots, and agains the boss of the cementery)