This is a rightmost derivation:

alpha = E + T
A = T
delta = T * F
A --> delta

alpha ==> beta where
beta = E + T * F

alpha = E +   T
            / | \
beta =  E + T * F


This is a leftmost derivation:

alpha' = E + T * F
beta'  = T + T * F


Example of ambiguity:

T --> T + T
T --> number

1 + 2 + 3

       T
    /  |  \
  T    +   3
 /|\
1 + 2


    T
 /  |  \ 
1   +   T
       /|\
     2  + 3

Left recursion:

E --> E + F

E ==> E + F ==> E + F + F ==> ...


Changing left recursion to right recursion:

T --> T + F
T --> F + T


Example of LL parsing for x + y:

S ==> E$ ==> T E' ==> F T' ==> 1...

        S
       / \
      E   $
    /   \
  T       E'
 /\     / | \
F  T'  +  T   E'
|  |      |\   \
x  _      F T'  _
          | |
          y _