Ive jus got a kx 85 but wats the petrol ment to go with plz help and how much oil mixed with petrol thx ?

a jus got a kx85 but it has petrol in it a whicha think is mixed with part oil but idk how much and idk how much i need ....eg..how much oil how much petrol and i dont want wierds amounts making the engine *** tho plz answer thx people