from tkinter import Button,Entry,Label,Tk,StringVar
def login():
    prozor1=Tk()
    t.destroy()
    prozor1.config(width=300,height=600)
    prozor1.title('ZBRAJANJE')
    def izlaz():
        prozor2=Tk()
        prozor2.config(width=300,height=600)
        prozor2.title('ZBRAJANJE')
        prozor1.destroy()
        def izlaz2():
            prozor2.destroy()
        gumb1=Button(prozor2,text='kraj',command=izlaz2)
        gumb1.place(x=100,y=100)
        a3=Label(prozor2,text='blablblablaba' )
        a3.place(x=10,y=50)
    gumb1=Button(prozor1,text='naprijed',command=izlaz)
    gumb1.place(x=100,y=100)
    a3=Label(prozor1,text='blabla' )
    a3.place(x=10,y=50)
t=Tk()
t.title('EOP')
t.config(bg='green',width = 300,height = 600)
l1=Label(t,text="REGISTER TO EOP",font=("Verdana",18),bg='pink')
l1.place(x=40,y=1)
l2=Label(t,text="USERNAME:",bg='pink')
l2.place(x=5,y=50)
l3=Label(t,text="E-MAIL:",bg='pink')
l3.place(x=5,y=100)
l4=Label(t,text="PASSWORD:",bg='pink')
l4.place(x=5,y=150)
e1=Entry(t,textvariable=StringVar(t, value='vanjavk'))
e1.place(x=80,y=51)
e2=Entry(t,textvariable=StringVar(t, value='vanjavk@hotmail.com'))
e2.place(x=80,y=101)
e3=Entry(t,show="*",textvariable=StringVar(t, value='123pro123'))
e3.place(x=80,y=151)
l5=Label(t,text="LOGIN TO EOP",font=("Verdana",18),bg='yellow')
l5.place(x=60,y=300)
l6=Label(t,text="USERNAME:",bg='yellow')
l6.place(x=5,y=350)
l7=Label(t,text="PASSWORD:",bg='yellow')
l7.place(x=5,y=400)
e4=Entry(t,textvariable=StringVar(t, value='vanjavk'))
e4.place(x=80,y=351)
e5=Entry(t,textvariable=StringVar(t, value='123pro123'),show="*")
e5.place(x=80,y=401)
b2=Button(text="LOGIN",font=("Verdana",15), command=login,bg='yellow')
b2.place(x=115,y=450)
t.mainloop()