from tkinter import *

w = Tk()

e  = Entry(w)
e.grid(row=0,column=0,columnspan=2,pady=5,padx=5)
b1 = Button(w, text="Load")
b1.grid(row=1,column=0,sticky=E)
b2 = Button(w,text="Save")
b2.grid(row=1,column=1,sticky=W)
b3 = Button(w, text="Execute!")
b3.grid(row=0,column=2,rowspan=2,sticky=NSEW)

w.mainloop()